OAKLAND, Calif. (AP) — In the first major league game with the new, unpopular extra-inning rule, automatic runner Marcus Semien began the bottom of the 10th on second base and scored on Matt Olson’s grand slam, sending the Oakland Athletics over the Los Angeles Angels 7-3 Friday night.Olson, whose alert throw from first base nailed Angels free runner Shohei Ohtani in the top of the 10th, connected with one out. Major League Baseball instituted the controversial extra-inning runner rule for this season to keep games from dragging on amid a compressed, 60-game schedule that started late because of the virus outbreak.After Semien took second, the A’s loaded the bases against Hansel Robles (0-1) on a hit by pitch, wild pitch and a walk.New Angels manager Joe Maddon brought in reliever Hoby Milner and, with a five-man infield in place, Olson hit the first pitch far over the right-field wall.According to STATS, Olson became the third player to hit a walkoff grand slam on opening day. He joined Sixto Lezcano (1980 Brewers) and Jim Presley (1986, Mariners).Burch Smith (1-0) went one inning for the win.The game went to the 10th tied at 3 after Jason Castro’s tying homer in the ninth against A’s closer Liam Hendriks.CUBS 3, BREWERS 0CHICAGO (AP) — Kyle Hendricks convinced new manager David Ross to let him finish a three-hitter, Anthony Rizzo homered and Chicago started the season by beating Milwaukee.Ian Happ also had a two-run drive and Ross got his first victory as a big league manager.Hendricks struck out nine and walked none in his first career opening-day start and fourth career shutout.Orlando Arcia had each of Milwaukee’s hits off Hendricks (1-0). After he singled with two out in the third for the Brewers’ first baserunner, he accepted a splash of sanitizer from a smiling Rizzo at first and cleaned off his hands.Ross came out to check on Hendricks with two out and a runner on first in the ninth. He decided to leave him in, and Keston Hiura bounced into a game-ending fielder’s choice on Hendricks’ 103rd pitch.Milwaukee right-hander Brandon Woodruff allowed four hits in five innings in his first career opening-day start. Woodruff (0-1) struck out five and walked one.ASTROS 8, MARINERS 2HOUSTON (AP) — Dusty Baker posted a win in his debut as Houston’s manager and the Astros, playing for the first time since their sign-stealing scandal rocked baseball, opened the season by beating Seattle.Michael Brantley hit a three-run homer to back Justin Verlander for Houston.The 71-year-old Baker posted a victory in his 3,500th regular-season game as a manager. The Astros got six solid innings from Verlander (1-0) to help them to their 14th straight victory over Seattle, setting a franchise record for most consecutive wins against any opponent. Verlander struck out seven and walked one as he became the ninth pitcher in MLB history to make 12 opening day starts. He allowed just three hits, but the first two were solo homers to give the Mariners an early lead.Seattle starter Marco Gonzales (0-1) took the loss.INDIANS 2, ROYALS 0CLEVELAND (AP) — Shane Bieber struck out 14 over six scoreless innings as the Indians, making a statement for minorities by wearing their road jerseys with “Cleveland” on the front, beat Kansas City.Bieber’s 14 strikeouts set a club record for opening day and are the most in the majors in an opener since Hall of Famer Randy Johnson also fanned 14 on March 31, 1996.Oscar Mercado and César Hernández drove in runs in the fifth for Cleveland, which was blanked over the first four innings by Royals starter Danny Duffy (0-1).Duffy was pulled in the fifth by first-year Royals manager Mike Matheny after 65 pitches. RBrad Hand worked around hitting the leadoff hitter in the ninth for a save.The Royals struck out 18 times.DODGERS 9, GIANTS 1LOS ANGELES (AP) — Max Muncy homered twice and doubled, Ross Stripling pitched seven neat innings and Los Angeles defeated San Francisco Giants for the second straight game.The Dodgers scored in every inning except the third and outhit the Giants 13-4. Mookie Betts notched his first RBI for Los Angeles in going 1 for 6. Muncy hit solo shots in the first off Tyler Anderson and in the sixth off Kevin Gausman. He and Justin Turner doubled back-to-back in the fourth.Corey Seager added three hits for the Dodgers. Stripling (1-0) allowed four hits, walked none and struck out seven.Jaylin Davis homered leading off the third. for the Giants, who remained winless under new manager Gabe Kapler.Tyler Anderson (0-1) gave up two runs and three hits in 1 2/3 innings. He walked three.BLUE JAYS 6, RAYS 4ST. PETERSBURG, Fla. (AP) — Cavan Biggio hit a three-run homer and Toronto began its still-in-progress odyssey by topping Tampa Bay.Earlier the Blue Jays announced they will play the majority of their home games at the stadium of their Triple-A affiliate in Buffalo, though it’s not yet certain when the park will be ready.Biggio singled to begin a three-run fourth inning off 36-year-old Charlie Morton (0-1), who made his first career start on opening day. Randal Grichuk, Rowdy Tellez and Teoscar Hernandez drove in the runs. Biggio also homered in the fifth for a 6-1 lead.Japanese slugger Yoshi Tsutsugo homered in his major league debut for the Rays. Blue Jays starter Hyun Jin Ryu allowed three runs and four hits in 4 2/3 innings. He struck out three, but also walked three before being replaced after throwing 97 pitches.Jordan Romano (1-0) finished fifth and got the first two outs of the sixth to get the win. Ken Giles worked a scoreless ninth for the save.REDS 7, TIGERS 1CINCINNATI (AP) — Free agent pickup Mike Moustakas drove in four runs, teaming with fellow newcomers Shogo Akiyama and Nick Castellanos, in Cincinnati's win over Detroit.Free agents Moustakas and Castellanos each got $64 million as cornerstones of the Reds' rebuild. They combined to produce Cincinnati’s first three runs, and Moustakas added a two-run homer to get the Reds off and running.Akiyama, signed as a free agent, singled home a run in his first at-bat as a pinch hitter. Joey Votto added a solo homer.Sonny Gray (1-0) fanned nine and gave up three hits in six innings. He extended his major league record to 34 consecutive starts without allowing more than six hits. Matthew Boyd (0-1) needed 26 pitches to get the first out and 30 overall in the first inning. He lasted five innings and gave up four runs on six hits. C.J. Cron homered for Detroit.METS 1, BRAVES 0NEW YORK (AP) — Yoenis Céspedes took advantage of the new designated hitter rule in the National League, launching a home run that sent Jacob deGrom and New York past Atlanta.Céspedes connected in the seventh off reliever Chris Martin (0-1) for his first long ball since his previous major league game on July 20, 2018. Seth Lugo (1-0) tossed two innings. Edwin Díaz struck out two in a hitless ninth for the save.Braves starter Mike Soroka allowed four hits in six innings. Marcell Ozuna doubled and went 1 for 4 in his Atlanta debut. Coming off consecutive Cy Young Awards, deGrom fanned eight and permitted only a broken-bat single and a walk. He was pulled after 72 pitches.MARLINS 5, PHILLIES 2PHILADELPHIA (AP) — Jesus Aguilar hit a two-run homer off Aaron Nola, Sandy Alcantara pitched into the seventh and Miami spoiled manager Joe Girardi’s first game in Philadelphia.Alcantara (1-0) allowed two runs — one earned — and three hits, striking out seven in 6 2/3 innings.Nola (0-1) gave up four runs and five hits, striking out seven in 5 1/3 innings. The Phillies have lost his last eight starts since a 3-2 victory at Boston last Aug. 20. Didi Gregorius lined a solo shot out to right in the fifth in his first game since signing a $14 million, one-year deal with the Phillies to reunite with Girardi. The Phillies cut it to 5-2 in the seventh when center fielder Jonathan Villar dropped Jay Bruce’s fly ball for a two-base error, allowing Gregorius to score. RED SOX 13, ORIOLES 2BOSTON (AP) — J.D. Martinez and Kevin Pillar each drove in three runs, and Boston rolled past Baltimore.Jackie Bradley Jr., Jose Peraza, Martinez and Pillar each doubled as part of a four-run third inning. Boston kept it going in the fourth, sending 11 batters to the plate and adding six more runs. Nathan Eovaldi (1-0) gave up just one run and five hits, striking out four over six innings in his first career opening day start. Baltimore starter Tommy Milone (0-1) got his first opening day nod after All-Star lefty John Means experienced arm fatigue. He gave up four runs, four hits, three walks, had a wild pitch and struck out five. Rio Ruiz homered in the seventh. Ron Roenicke earned his first managerial win since a five-year tenure with the Brewers ended in 2015. RANGERS 1, ROCKIES 0ARLINGTON, Texas (AP) — Lance Lynn struck out nine in six sharp innings and Texas inaugurated its new retractable-roof stadium with a win over Colorado.After 48 seasons of playing home games outside in the Texas heat, the Rangers had the roof closed for their first game at $1.2 billion Globe Life Field.The Rangers got their first hit off Rockies starter German Marquez after Lynn (1-0) had thrown the last of his 108 pitches in his first opening day start.Danny Santana had a one-out double in the sixth, and scored on a two-out double by Rougned Odor that chased Marquez (0-1). The Rockies right-hander retired the first 12 batters and struck out six and walked three. Jesse Chavez and Jonathan Hernandez both pitched a scoreless innings. Jose Leclerc struck out two in the ninth for the save in the Rangers’ first 1-0 win in a home opener since 1980. CARDINALS 5, PIRATES 4ST. LOUIS (AP) — Jack Flaherty struck out six and didn't walk a batter in seven solid innings, Paul DeJong hit a two-run homer and St. Louis opened the season by beating Pittsburgh.Tyler O’Neill and Dexter Fowler added solo homers for St. Louis.Flaherty did not give up a run until Jacob Stallings hit two-out, two-run single just under the glove of first baseman Paul Goldschmidt in the seventh.St. Louis built up a 3-0 cushion on homers in the fifth. Yadier Molina added a run-scoring hit in the sixth.Kwang Hyun Kim allowed two runs before retiring three successive hitters to get the save in his major league debut. Pittsburgh starter Joe Musgrove allowed three runs and five hits over 5 2/3 innings. He fanned seven and walked three.The Pirates, under first-year manager Derek Shelton, fell to 71-63 in season openers.TWINS 10, WHITE SOX 5CHICAGO (AP) — Max Kepler homered against ace Lucas Giolito in his first two at-bats and Minnesota beat Chicago.White Sox slugger Yoán Moncada had three hits, including a three-run shot off José Berrios in the second inning that tied the game at 5.Jorge Polanco answered with a two-run single in the fourth inning to put Minnesota ahead for good.Giolito and Berrios struggled, and a duel between the All-Star right-handers never materialized. Giolito (0-1) allowed seven runs, six hits and three walks before being pulled with two outs in the fourth in his first opening day start. Berrios yielded five runs and seven hits in four innings in a no-decision.Trevor May (1-0), the first of four Twins relievers, pitched a scoreless fifth.Jake Cave, who started in center field in place of injured Byron Buxton, had two hits and drove in two runs for Minnesota. Luis Arrraez also had two hits and had two RBIs for the Twins.PADRES 7, DIAMONDBACKS 2SAN DIEGO (AP) — Eric Hosmer hit three-run doubles in consecutive innings to ruin Madison Bumgarner’s Arizona debut and give San Diego a victory in Jayce Tingler’s first game as manager.The six RBIs tied Hosmer’s career high and backed 24-year-old right-hander Chris Paddack (1-0), who threw six scoreless innings in his first opening day start.The 30-year-old Bumgarner (0-1) allowed only two hits before struggling in the sixth. He allowed three runs and four hits in 5 2/3 innings, with four strikeouts and three walks.Paddack held the Diamondbacks to four hits while striking out four and walking one. Arizona’s Kole Calhoun homered off Emilio Pagán in the seventh. ___More AP MLB: https://apnews.com/MLB and https://twitter.com/AP_Sports