BOSTON (AP) -- Detroit Tigers manager Jim Leyland had a theory about why Doug Fister looked completely different after a shaky start.
Fister walked three and plunked a hitter in the first seven batters he faced, but settled down to throw seven shutout innings as Tigers beat the Boston Red Sox 3-0 Monday in a matchup of teams with the AL's best records.
''This is what I think, and I'm probably crazy,'' the veteran manager said. ''People have talked about this park for 100 years and I think at the beginning of the game he was being a little bit careful, and I thought he got more aggressive as the game went on - and I thought it helped him.''
''Early on, I think he was being careful like a 1,000 pitchers have done before him. It's hard to convince him that you have to be aggressive in this ballpark because if you don't you'll get burnt. I don't have idea if that's accurate, but that's what it seemed like to me,'' he said.
Fister (12-7) rebounded from a miserable start in his previous outing, holding Boston to four hits while walking four and striking out four. In his last start, he gave up 13 hits and seven runs in a loss to Oakland.
''Keeping the ball down, throwing pitches that I needed to induce the double plays,'' the right-hander said was the difference.
The Tigers won despite missing Miguel Cabrera for the third straight game. He has been sidelined by a strained abdomen, though general manager Dave Dombrowski said the Triple Crown winner has been more hampered by a groin problem.
''I feel better,'' Cabrera said as he stopped briefly while walking through the clubhouse.
Asked if he thought he'd play on Tuesday, the slugger smiled and said, ''I hope so.''
Prince Fielder and Andy Dirks each drove in a run for the AL Central-leading Tigers, who won for the fourth time in five games.
The AL East-leading Red Sox lost for just the second time in nine games.
John Lackey (8-12) was the tough-luck loser, giving up three runs on seven hits over 7 1-3 innings. It was the 11th time Boston's been shutout, six coming when he's pitched.
''I don't know exactly (why),'' he said when asked about the lack of run support. ''I haven't looked that close at it.''
Jose Veras, the fourth Tigers pitcher, worked the ninth for his 21st save and second with Detroit, finishing the six-hit shutout.
The Tigers turned three double plays, two in the opening two innings.
''(Fister) got a number of ground-ball double plays when he needed to,'' Boston manager John Farrell said. ''Opportunities the first, the second, the fifth, then again in the seventh. We put men on base, just didn't get a timely hit.''
Detroit broke a scoreless tie with two runs in the seventh. Victor Martinez singled leading off and scored on Dirks' triple to the triangle just over the glove of center fielder Jacoby Ellsbury. Dirks scored on a double-play grounder, making it 2-0.
Fielder's sacrifice fly made it 3-0 in eighth.
The Red Sox didn't get their first hit off Fister until Daniel Nava, who went 3 for 3 with two doubles, singled with two outs in the fourth.
Boston had the first two runners reach in the seventh, but Jarrod Saltalamacchia bunted into a forceout at third and the next two hitters bounced out.
Austin Jackson opened the game with a double, but Lackey got the next three hitters - with help from second baseman Dustin Pedroia, who ranged far to his left to make a play on Martinez's inning-ending grounder.
NOTES: Cabrera took batting practice with the Tigers' starters and looked as if he was swinging freely. He was smiling when he walked off. He stopped to sign autographs and take a few pictures with fans on the field near the Tigers' dugout. ''He was in good spirits and I think he was feeling much, much better to be honest with you,'' Leyland said after the game. ... Fielder hit third for the first time since Aug. 3, 2010. ... A male fan was hit in the head by a foul ball off the bat of Victorino in the sixth inning, but he walked up for medical help with a towel over his face. ... Farrell said RHP Clay Buchholz, on the DL since early June with a strained neck, will make his third rehab start Thursday instead of Wednesday because his wife is expected to have labor induced for the birth of their second child. ... Leyland spoke highly of SS Jose Iglesias, acquired from Boston in a multiplayer deal on July 30. ''He's very gifted, he's very competitive and very instinctive,'' he said. ''This kid's a very interesting guy, very talented. We're very fortunate to have him. We were lucky to get somebody like that when we were in dire need of somebody.'' ... Leyland gave closer Joaquin Benoit the day off after he pitched in three of the previous four games.