CHICAGO >> Boston right fielder Shane Victorino was running the bases in the sixth when his left hamstring started to bother him, and he was replaced in the field in the bottom of the inning today. He also missed games on Friday and Saturday with a back injury.

“I didn’t have the strength that I usually have in trying to pull my leg up, and I felt a little something grab,” Victorino said.

Boston manager John Farrell said Victorino was day to day and the team would proceed cautiously.

The White Sox beat the Red Sox today 6-4 when Jon Lester served up a three-run homer to Adam Dunn in the first inning and took his first loss of the season.

“You know, it was a night where he had to battle,” Boston manager John Farrell said. “He gets the two quick outs in the first inning, then after the base hit and the walk it was a 2-0 cutter that stayed in the middle of the plate to Dunn, who’s been swinging the bat well of late, so we find ourselves down 3-0. Then they bunched some hits the other way.”

Alejandro De Aza and Alexei Ramirez added consecutive RBI doubles in the second as Chicago took advantage of an ineffective Lester (6-1) to earn its fifth win in seven games in the opener of an eight-game homestand. The White Sox scored each of their runs with two outs.

“The first inning’s good, but you know for me, that next inning when you get a couple doubles and you score like that, that’s a good sign,” manager Robin Ventura said.

Jarrod Saltalamacchia hit a two-run homer for the Red Sox, who had won five in a row. Saltalamacchia made a bid for a second two-run shot, but Dayan Viciedo brought in his drive on the warning track in left-center with the White Sox clinging to a 6-4 lead in the seventh.

Lester was trying to become the first left-handed starter to win his first seven decisions for Boston since Roger Moret in 1973. But he was shaky in the first couple of innings while falling to 4-5 in 10 career games against the White Sox to go along with a 5.43 ERA, his highest against any AL team.

“Chicago, for some reason, I don’t feel like I’ve ever pitched well here for whatever reason,” Lester said. “It is what it is, and it always goes back down to executing pitches at the right time, and I didn’t execute the pitch in the first inning. That changed the whole momentum of the game.”

Lester retired his first two batters before running into trouble. Alex Rios singled to extend his hitting streak to 15 games and Paul Konerko walked before Dunn drove a 2-0 pitch to right for his fifth homer in seven games and No. 11 on the year.

“Just didn’t do a good job there,” Lester said. “Ended up leaving a guy that’s got stupid pop cutters down the middle and he did what he’s supposed to with it.”

Dunn also walked before Viciedo singled home Ramirez to make it 6-2 in the fifth. The burly slugger is batting .360 with 13 RBIs in his last seven games, raising his average 39 points to .172 for the year.

“When he’s right, he can do a lot of damage,” Ventura said. “His pitch selection is good. I don’t know mechanically exactly what it is but when a guy knows he’s in the right position to hit and he’s more confident, it comes down to pitch selection.”

Lester retired the side in order in the sixth, and that was it for him. He allowed five earned runs and seven hits, walked three and struck out two.

While Lester struggled, Dylan Axelrod (2-3) pitched six effective innings to win his second straight start. The right-hander gave up two runs and four hits.

“It’s easy to have a lead and pitch to contact and just let the defense work,” he said.

Matt Thornton yielded Will Middlebrooks’ two-run double in the seventh and Jesse Crain extended his scoreless streak to 17 innings before Addison Reed finished for his 15th save in 16 chances.

With one out and a runner on first in the ninth, Middlebrooks hit a drive that De Aza caught at the wall in center field. Konerko then made a diving stop on Stephen Drew’s grounder and flipped the ball to Reed covering first to end the game.

NOTES: The Red Sox activated closer Andrew Bailey from the 15-day disabled list. He had been out since April 29 with right biceps inflammation. … Drew returned to the lineup after missing two games with a sore back. … Red Sox 2B Dustin Pedroia singled in the fourth to extend his hitting streak to 12 games. … Farrell said C David Ross (concussion) threw and rode a bike for 30 minutes. He will try to increase the intensity of his work on Tuesday. “He’s moving in the right direction,” Farrell said. … LHPs Felix Doubront (3-1, 6.03 ERA) of the Red Sox and Jose Quintana (2-1, 3.97) of the White Sox are slated to pitch Tuesday.