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The Detroit Tigers sent Doug Fister to the mound and jumped out to a big lead in the rubber game of a key weekend series against the Baltimore Orioles.

It quickly fell apart from there.

Fister was knocked out in the fourth inning and the Tigers went on to a 7-5 loss on Sunday.

"It's plain and simple — I didn't execute," Fister said. "I was very poor at making adjustments and they made me pay for it."

Detroit jumped all over rookie Wei-Yin Chen (12-7), scoring five times with one out in the first. Omar Infante hit a solo homer, Miguel Cabrera walked and Prince Fielder singled to left before Jhonny Peralta drove a 2-0 pitch over the wall in center to make it 4-0.

Delmon Young singled and scored on Jeff Baker's double before Chen retired two in a row to end the inning.

"We let him off the hook there," Baker said. "We had him on the ropes and couldn't back it up with another inning. We needed to get him out of the game and get into their bullpen early."

Still, the Tigers were feeling pretty good after the strong start. After all, Fister was 6-1 with a 1.97 ERA in his previous eight starts.

"When we put five runs up, I'm thinking we're going to win this game without a doubt," Alex Avila said. "You're feeling pretty good at that point."

The Orioles responded in the second. Chris Davis connected for his 20th homer, Nick Markakis had an RBI double and J.J. Hardy came up with a two-run double that trimmed Detroit's lead to 5-4.

"It sounds crazy when you are talking about a solo homer, but I thought Davis turned the whole game around," Baltimore manager Buck Showalter said. "We were down big, but that showed everybody that we were going to get right after it."

Nate McLouth, who entered with just four RBIs for the season, put the Orioles in front with a two-run triple with two out in the fourth, and Davis drove him in with a base hit. That knocked Fister out of the game, having allowed as many earned runs as his previous five starts combined.

"He was just out of whack — he wasn't good today," manager Jim Leyland said. "He knows what to do with a lead, but he just wasn't crisp. I just don't think he felt right."

McLouth, Markakis and Mark Reynolds each had two hits for the Orioles, who have won five of seven, including the last two of the key set at Detroit.

The Orioles lead Detroit by two games in the race for the second wild-card spot in the American League. The Tigers had won 17 of 20 at Comerica Park before dropping the last two this weekend.

"It's crucial for us to try to win a series against a team like that," left fielder Quintin Berry said. "But they came out and took care of business, and we didn't. We've got two more home series coming up, and we have to pick it up."

Fister allowed eight hits, struck out six and walked three.

"A loss is a loss that stings just as much as any other one," he said. "It's letting teammates down, not making adjustments and making mistakes. I just have to come back from this."

Detroit put two runners on with no outs in the seventh but Darren O'Day struck out Cabrera on three pitches and got Fielder to bounce into a double play.

Jim Johnson worked the ninth for his 37th save in 40 chances. The right-hander is now tied with Gregg Olsen for the second-most saves by an Oriole. Randy Myers had 45 in 1997.

NOTES: Erik Bedard was the last Oriole to win 12 or more games in a season, picking up 13 victories in 2007. ... With Chen's next win, he will tie Hong-Chih Kuo for the second-most career victories by a Taiwanese-born pitcher. Chien-Ming Wang is the leader with 61, and also has the single-season record with 19.