NEW YORK -- In the sixth inning Tuesday, the specter of Houston Astros co-aces Dallas Keuchel and Justin Verlander loomed over the remainder of the American League Championship Series.Then the seventh and eighth innings of Game 4 happened, and the New York Yankees' bullpen-heavy blueprint suddenly looked a little sturdier than the Astros' top-heavy rotation approach.The Yankees busted out for six runs over their final two at-bats against Lance McCullers Jr. and wave after wave of overwhelmed Astros relievers. New York rallied to beat Houston 6-4 and tie the series at two games apiece.Game 5 is scheduled for Wednesday afternoon at Yankee Stadium. Thanks to the Yankees' stunning comeback, it will not, as it appeared for a little while Tuesday, serve as a pennant-winning coronation for the Astros, who are scheduled to send Keuchel to the mound against Yankees right-hander Masahiro Tanaka.Keuchel has thrown 13 scoreless innings in two career playoff starts against New York, whom he blanked over seven innings Friday in a Game 1 win."That's always in the back of your head," Yankees manager Joe Girardi said of Keuchel pitching Game 5. "I was focused on trying to keep it as close as we could. Give us a chance to win. Bullpen, just do your job, and they did."The Astros entered the seventh inning up 4-0 behind McCullers, who had allowed one hit and one walk while completing six innings for the first time since June 8. However, manager A.J. Hinch sent McCullers out for the seventh, which began with Aaron Judge crushing a first-pitch homer to center field.Hinch then pulled McCullers, and the performance of four relievers proved why he went as far as he possibly could and then some with his starter. Chris Devinski gave up a triple and a sacrifice fly to the first two batters he faced, Didi Gregorius and Gary Sanchez, before Joe Musgrove recorded the final two outs of the seventh.Yankees right-hander Chad Green, who allowed an unearned run in the seventh, threw a perfect eighth inning to set the stage for the completion of the comeback in the bottom of the frame."Tack-on runs are the difference in a lot of games," Yankees infielder Chase Headley said. "For us to be able to climb back in it a little bit, and then (for) 'Greenie' to go back out there and get us back in quick, that's a big deal."Musgrove gave up singles to Todd Frazier and Headley to open the eighth, at which point Hinch went to closer Ken Giles for the six-out save. Giles wound up retiring just one of the five batters he faced, and he gave up the go-ahead hit, a two-run double by Sanchez, that made Yankee Stadium shake as it did during the Yankees' dynastic years."It's painful," Giles said. "I let the whole team down."The Yankees ended up sending 10 batters to the plate in the bottom of the eighth, which lasted nearly 40 minutes."It's not a great visual from my side of the dugout," Hinch said. "We just couldn't get the inning to end. We were trying to match up and make pitches. They were putting really great at-bats together."Aroldis Chapman threw a perfect ninth inning to earn the save for the Yankees, whose relievers have combined to post a 2.09 ERA in 43 innings this month.Astros relievers, on the other hand, have a 6.21 ERA in 24 1.3 innings, a performance that threatens to render irrelevant the brilliance of Keuchel and Verlander, the latter of whom was acquired Aug. 31 and is in line to start Game 6 on Friday night.Counting the postseason, Keuchel and Verlander have combined to go 12-2 with a 1.74 ERA in 14 starts.Hinch spoke confidently of his relievers Tuesday night, but it sure looks as if the best way for the Astros to reach the World Series for the second time is to make sure nobody other than Keuchel and Verlander sees the mound over the next two games."Dallas Keuchel, he's pretty good at getting deep in the game," Hinch said. "We'll hand the ball to this bullpen with the lead tomorrow feeling good about it if that's the case."After Tuesday, so will the Yankees.