BOSTON -- Perfection took a sharp left turn at Fenway Park for the Baltimore Orioles Thursday afternoon, turning what began as a memorable pitching performance by Wei-Yun Chen into a three-alarm fire drill in the ninth before the Red Sox finally succumbed, 10-6, to the AL East leaders.

Chen took a perfect game into the sixth inning, retiring the first 16 Sox batters before Dan Butler doubled off the wall in left-center for his first major-league hit.

By then, the Orioles had built an 8-0 lead, having cuffed around Sox starter Brandon Workman for six runs in the third and adding a two-run home run by Caleb Joseph in the fifth.

Xander Bogaerts broke Chen’s shutout bid with a home run, his 11th of the season, in the seventh, but the lead was 10-1 entering the bottom of the ninth, RBI doubles by Kelly Johnson and Ryan Flaherty tacking on two more runs in the top of the inning.

But it took three Orioles relievers to quell a five-run Sox uprising in the bottom of the ninth, fueled by a two-run double by Daniel Nava and a three-run home run by Carlos Rivero, the first of his big-league career.

The Sox had the tying run on the on-deck circle when Bogaerts, who had doubled in the inning, grounded into a force play to end the game.

The victory reduced the Orioles’ magic number in the AL East to eight games -- any combination of Baltimore wins and Toronto losses will give the Orioles their first division title since 1997.

The Sox, meanwhile, were officially eliminated from postseason competition, their record falling to 63-83 with 16 games to play. They need to go 7-9 to finish ahead of the last-place 2012 team, which went 69-93.