Chen gave up five runs in the first inning, but the Orioles rallied to get him a win, 7-5 over the Detroit Tigers in front of 40,511 at Comerica Park. The O's won two of three there this weekend.
Detroit got first-inning homers from Omar Infante and Jhonny Peralta to go ahead by five before the Orioles rallied to get the lead. Chen improves to 12-7 with an ERA of 3.87.
The Orioles produced their third rally to win when behind by five over the last 18 games. They also did it July 31 against the Yankees in New York and Aug. 7 at home vs. Seattle.
The Tigers went 5-for-8 with three extra-base hits in the first inning off the lefty, but were just 2-for-13 over the next four innings, as Chen got through five to qualify for one more win than Zach Britton had last year when he led the club with 11.
Darren O'Day got out of a huge jam in the seventh when a single and error put two men on for the middle of the order. But he struck out Miguel Cabrera looking and got Prince Fielder to hit into a 4-6-3 double play.
Jim Johnson pitched the ninth to record his 37th save. That total ties Gregg Olson for the second-most in a season in O's history behind only Randy Myers, who had 45 in 1997.
The O's rally began with a four-run second which included a Chris Davis solo homer, Nick Markakis RBI double and J.J. Hardy two-run double. For Hardy, the two-run two-bagger ended a nine-game, 37 at-bat RBI drought.
The Orioles scored three in the fourth to get the lead on a Nate McLouth two-run triple that made it 6-5. An Adam Jones RBI single added an insurance run. McLouth was 2-for-19 over his last five games and had just one RBI over his previous seven games.
After going 1-for-12 batting with runners in scoring position in the series' first two games, the Orioles went 4-for-6 with RISP in the first four innings today.
The Orioles improve to 66-55 on the season and 34-26 on the road. They end the season series with the Tigers at 3-3 and have now won four straight road series.
The Orioles are now 42-18 in games decided by two runs or less.
As they head to Texas, they go with the momentum of a big series win over another AL wild card contender and with five wins over their last seven games, 14 in the last 20 and 20 over their last 31 games.