For all the talk about the Yankees not having a true ace, one of their pitchers quietly is doing a pretty good impression of one.

Nathan Eovaldi entered Monday night on an American League- best eight-game winning streak, and had he received any run support, he would have run it to nine. As it was, he and the Yankees happily took the result, a 1-0 walk-off victory over the Astros in front of 37,125.

The Yankees (69-55), who pulled into a virtual tie with the idle Blue Jays in the AL East, won it in the ninth on Carlos Beltran's sacrifice fly to deep centerfield that drove in Brett Gardner.

"Every game as we move forward has a lot of meaning to it," Joe Girardi said. "To get a great pitching performance by him, eight strong innings, when our bullpen is pretty tired, I thought was huge."

Gardner led off the ninth with a walk off former Mets lefthander Oliver Perez and went to second on a wild pitch. Alex Rodriguez (0-for-3) was walked intentionally and Brian McCann walked to load the bases. In came Chad Qualls, and Beltran, swinging first pitch, sent the game-winning fly ball to center.

"Just trying to be as aggressive as I can and hopefully do what just happened," Beltran said. "I think the player of the game has to be Eovaldi. He just pitched an amazing game."

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Eovaldi, 25, was 8-0 with a 3.29 ERA in his previous 11 starts and continued to excel. He limited the AL West leaders, who entered No. 1 in the league with 169 homers, to four hits and three walks. He struck out seven, shut down the Astros with runners in scoring position (0-for-7) and stranded eight runners.

"Might have been the best slider he's had all year," Girardi said.

McCann, who threw out pinch runner Jake Marisnick for the second out of the ninth, used the word "filthy" in describing Eovaldi.

"He did whatever he wanted to do," McCann said. "He pitched an amazing game. and I feel he's pitched that way since the Miami game."

That was June 16 in Miami, when he allowed eight runs in two-thirds of an inning.

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Eovaldi (13-2, 4.00) said the difference for him since then -- and really all season -- has been the development of his off-speed pitches and the continual refinement of his splitter, a pitch he started throwing late last season.

"Just being able to use the split has helped me out a lot," Eovaldi said. "At the beginning of the season, I didn't have as much confidence in it as I do now. I feel like I'm able to locate it when I'm behind in counts. It's been pretty big for me."

Houston's Scott Feldman matched Eovaldi with eight shutout innings of his own. Feldman came in an unimpressive 5-5 with a 4.05 ERA but was 1-0, 1.89 in three previous August starts. He allowed six hits and no walks and struck out seven.

Eovaldi was throwing 101 mph in the first inning and still notching 100 mph in the eighth. He struck out the game's first two batters, Jose Altuve and Marwin Gonzalez, on 84-mph curves, and retired the last batter he faced, Carlos Gomez, on a fly ball to center on a 92-mph splitter.

"Tonight was the best I've felt about an outing," Eovaldi said.