HOUSTON -- Houston Astros reliever Ryan Pressly left Game 6 of the American League Championship Series on Saturday night due to right knee discomfort.

In the top of the third inning, Pressly fielded a comebacker off the bat of the Yankees' Didi Gregorius and charged at him as Gregorius ran up the line. Pressly, who had arthroscopic surgery on the same knee in August, tried to halt his momentum as he got close enough to apply the tag but immediately pulled up and grimaced.

Television cameras captured Pressly heading through the dugout and back into the clubhouse along with a member of Houston's training staff. He is listed as day to day.

The pitch Pressly threw to Gregorius turned out to be his only one in the game, but it was big -- there were two outs and the bases were loaded in the third inning. The out he recorded nipped that Yankees' rally and preserved a two-run Houston lead.

Pressly was replaced by rookie Jose Urquidy to start the fourth inning. His departure could leave Houston manager AJ Hinch short of arms. The Astros used a bullpen day in lieu of a traditional starter in Game 6. Urquidy was the fourth pitcher Hinch used over the first four innings of the game.

Pressly, 30, was 2-3 with a 2.32 ERA and three saves during the regular season, which he resumed in late September after surgery. He struggled at the outset of the postseason and has a 13.50 playoff ERA after his outing on Saturday.

Houston was leading New York 3-2 in the fifth inning. The Astros lead the best-of-seven ALCS 3-2 and are bidding to close out the Yankees to win the AL pennant for the second time in the last three seasons.