DETROIT - The Tigers on Friday snapped their season-high five-game losing streak, while the Red Sox extended their own skid to four.
Rubby De La Rosa, again starting in place of Clay Buchholz, paid a steep price for letting some pitches sail too high.
Ian Kinsler and Torii Hunter hit back-to-back homers in the fifth inning. Victor Martinez also homered after De La Rosa had left the game.
De La Rosa (1-1) gave up four runs, nine hits and two walks. He had five strikeouts over 5 2-3 innings.
In his first start of the season, he threw seven scoreless innings against Tampa Bay last week.
"I feel almost 100 percent like last time," De La Rosa said. "I just missed more pitches."
Boston has lost four straight after winning seven in a row. The Red Sox are averaging fewer than three runs during the losing streak.
"Offensively, we're scuffling," Red Sox manager John Farrell said. "We've had a rough go with runners in scoring position."
The Red Sox hope to end a trend this weekend.
In their last seven series, they've been swept four times and have won each game in the other three matchups.
"We became so accustomed to being consistent," Farrell said. "The last two and a half weeks have been difficult."
Kinsler and Hunter cleared the fences during a three-pitch sequence in the fifth, giving the Tigers a 4-1 lead.
"They squared (De La Rosa) up when he was up in the strike zone," Farrell said.
The Red Sox pulled within two runs in the sixth when Dustin Pedroia reached on Romine's throwing error, advanced to third on David Ortiz's single through the right side against a shifted infield and scored on Jonny Gomes' sacrifice fly.
Detroit's Ian Krol and Joba Chamberlain each threw an inning of scoreless relief and Joe Nathan pitched the ninth in a non-save situation.