HOUSTON — Masahiro Tanaka hadn’t allowed a run in his previous two outings and he couldn’t afford anything less Friday against the Astros.

Unfortunately for the Yankees, he couldn’t match those results, as they lost Game 1 of the ALCS, 2-1, to the Astros with Tanaka outpitched by Dallas Keuchel — just as he was in the 2015 AL wild-card game.

Largely staying away from his splitter — which he said he didn’t think was as good as in his most recent outings — Tanaka didn’t give up a hit Friday until Jose Altuve reached on an infield single in the fourth.

Because Tanaka had no margin for error, though, it was costly.

With Carlos Correa at the plate next, Altuve swiped second, which allowed him to score on Correa’s single to left. Correa moved to second on a grounder to second by Marwin Gonzalez and came around on Yuli Gurriel’s single to make it 2-0.

“The stuff was there, but when I had runners on base I needed to command my pitches better,” Tanaka said through an interpreter.

On another night, the two runs on three singles in the inning wouldn’t have been too much to overcome.

With Keuchel again dominating the Yankees’ offense, Tanaka already had given up too much.

Really, Tanaka had to be as good as he was both against the Blue Jays on Sept. 29, when he struck out 15 in seven shutout innings and on Sunday, when he blanked Cleveland for seven frames in Game 3 of the ALDS.

Tanaka had been mostly dreadful versus the Astros, going 0-2 with a 10.38 ERA in four regular-season starts in his career. And in his one playoff outing before this season, he was also outpitched by Keuchel, when he allowed two runs in a 3-0 defeat in that wild-card game in The Bronx.

Making Tanaka’s night even worse was the line drive he took off his leg from Josh Reddick to lead off the bottom of the sixth.

Tanaka recovered to make the play and get the out. After a visit from the trainers, Tanaka allowed another single to Altuve, but then got Correa and Gonzalez to end the inning.

Tanaka’s night was done after that, with the right-hander permitting just the two runs over six innings and 89 pitches before he was replaced by Chad Green in the seventh.

“That’s not the reason I took him out,” Girardi said. “I took him out because I thought he gave us everything he had and I thought it was time to make a change. But just another great outing.’’