CHICAGO – Paul Konerko hit a grand slam that wrecked Jon Lester’s bid for his 20th win, and the Chicago White Sox beat the Boston Red Sox 8-2 Thursday night in a game delayed because of a power failure.

The game was held up for 21 minutes in the sixth inning when most of the stadium lights went out. A power outage in the area was the cause.

Konerko connected for his 39th homer of the season and the ninth grand slam of his career. The fourth-inning shot off Lester (19-9) made it 6-2. Dayan Viciedo chased the Red Sox ace with a two-run homer in the fifth.

Lester was trying to become the first Red Sox left-hander in 57 years to win 20 games. He gave up eight runs and nine hits in four-plus innings in his final start of the season.

Victor Martinez homered for Boston, which has lost four of its last five.

Juan Pierre stole three bases, giving him a career-high 66, as the White Sox finished 6-1 against the Red Sox. Chicago has won 7 of 8 since being eliminated from the AL Central race.

White Sox starter John Danks (15-11) pitched six innings and allowed two runs on five hits.

Lester’s 15-inning scoreless streak ended in the first inning. Pierre hit a leadoff single, stole second and third and scored on a single by Andruw Jones.

Pierre singled in the third, stole another base and scored on Jones’ bloop single.

Lester ran into bigger trouble in the fourth. He allowed a leadoff double to Alejandro De Aza and issued walks to Pierre and Alexei Ramirez before Konerko connected for the game-breaking hit.

Marco Scutaro led off the Boston third with a double. After a sacrifice by Darnell McDonald, Martinez hit his 20th home run.

NOTES: Before the game, Konerko acknowledged he would like to remain with the White Sox but also expressed interest in leaving his options open. Konerko is about to finish a five-year deal he signed after the White Sox won the World Series in 2005. “Obviously it’s a business, so they have to figure out payroll stuff and when they do that, then hopefully I’m in their conversation, as far as being brought back,” he said. … Pierre stole 65 bases for the Florida Marlins in 2003. … Danks and reliever Sergio Santos combined for six consecutive strikeouts.