The 22-year-old right-hander pitched on consecutive days for the first time Thursday, helping fellow rookie Phil Hughes beat the Tampa Bay Devil Rays 3-1 to keep alive New York's slim hopes in the AL East.
Chamberlain struck out B.J. Upton to escape a jam with runners at first and second in the eighth inning. The Yankees have brought him along slowly, but Joba Rules have been eased during the past week, putting him in position where he can be used relatively freely in the postseason.
"He's always said that he could do it, and tonight was a great opportunity after clinching to give him a chance," Yankees pitching coach Ron Guidry said. "I don't think he was as sharp as he normally has been, but I think he did a good job. He got into trouble, he got out of trouble. That's the mark of a good pitcher."
Chamberlain has allowed just one earned run in 23 2/3 innings, a 0.38 ERA, since joining the Yankees in early August and has struck out 34. He said he felt good after the 20-pitch outing in which he allowed a single and also hit a batter.
"It's kind of interesting to see how your body reacts, and it was good. It's been good all year," the 22-year-old right-hander said. "It came back great. My body felt good, so it was another test that, hopefully, I passed."
Manager Joe Torre also liked what he saw.
"He seemed fine. The first thing we checked was Joe Kerrigan in the bullpen to make sure that he had an easy time doing what he was doing, and there were no issues," Torre said, adding that he'd like to bring Chamberlain in during the middle of an inning in his next outing, probably Sunday.
Jose Veras pitched the ninth, completing a six-hitter for his second career save.
New York, which rested Alex Rodriguez, Derek Jeter and four other regulars, closed within two games of first-place Boston with three games to play. The Yankees finish the regular season with a weekend series at Baltimore before opening the playoffs, likely at Cleveland.
"There's a mathematical chance," center fielder Johnny Damon said of the division race. "There's stuff we can't control. All we can control is what we do. ... We just need to try and finish up the best we can."
Tampa Bay wasted a good performance by Scott Kazmir, who allowed one run and three hits in six innings. The 23-year-old left-hander fanned 10 to pass Johan Santana for the major league strikeouts lead with 239.
Kazmir limited the Yankees to Bronson Sardinha's third-inning, infield single -- the rookie's first major league hit -- until another rookie, Alberto Gonzalez, lined a single to left field with one out in the sixth. Damon followed with a RBI double that made it 1-1. Damon went 10-for-15 in the series and raised his average to .269 -- his highest since late May.
"I tried to get the strikeouts out of my head," Kazmir said. "I just wanted to go out and attack the strike zone and get as deep as I could into the ball game. With the fans behind you like they were, it just makes it all the much more special."
"There was a lot of goofing around that a manager doesn't stand for, but considering the time of year and what happened yesterday, they had fun and that's fine with me," Torre said. "The thing about it, they were out there. Not that they didn't stray in and out, but they were joking around and pulling for guys. It was a very comfortable evening, I guess you could say. It was fun for me."
- Chien-Ming Wang or Andy Pettitte will start the playoff opener next week. The Yankees are hopeful that Roger Clemens, who is rehabbing a strained left hamstring, will be ready to pitch Game 3.
- Pena's homer was his 18th in last 36 games. He has 11 in September, tying the Devil Rays record for home runs in a month set by Jonny Gomes in April 2006.
- Young's fourth-inning single broke Tampa Bay's record for hits in a season by a rookie. He has 185, one more than Rocco Baldelli had in 2003.