Rays manager Joe Maddon felt Sonnanstine made a mistake by straying from his fastball.
"He didn't use the fastball as often today," Maddon said. "He got hurt on his breaking balls. He wasn't as aggressive with his fastball tonight. ... I think if he stayed closer to his plan in Boston, he would've had a better night. He's learning. He's a battler. And he doesn't cave. He did some things pretty good, but that one inning beat us."
That one bad inning came in the fourth and began with an infield single by barrel-chested Red Sox slugger David Ortiz, who had hit an RBI triple to account for one of Boston's two runs in the first, and then it snowballed the way of baseball's best club.
One out after Ortiz's single, Sonnanstine hit Mike Lowell on the left hand and J.D. Drew followed with a single to load the bases. Jason Varitek singled to drive home Ortiz before Coco Crisp and Julio Lugo hit back-to-back two-run doubles to give the Red Sox a 7-2 lead.
"The breaking ball for Lugo, I thought, was the big hit for them," Maddon said.
Sonnanstine allowed seven earned runs on eight hits in five innings, unable to throw six innings for just the fourth time in 15 starts this season, but the third time in his last four starts. Though he now owns 63 strikeouts and just 17 walks, the Rays have won just three times when he's started this season.
Despite twice falling in a hole, the Rays continued to fight back.
They answered the Red Sox's two-run first in their half of the frame as Carlos Pena hit a two-run homer, his career-best 28th long ball of the season, to tie the score at 2.
Trailing, 7-2, Akinori Iwamura hit his first home run since June 23, a three-run homer off Red Sox starter Jon Lester that gave the Rays hope by cutting the lead to 7-5.
"We kept coming back," Maddon said. "Aki's home run was big for us. We had opportunities but that five-run inning is so hard to overcome."
Rays shortstop Josh Wilson booted Ramirez's two-out ground ball in the seventh to allow the Red Sox's eighth run to score. But Boston gave back the run when second baseman Dustin Pedroia dropped Carl Crawford's line drive with two outs in the seventh, which allowed a run to score to make it 8-6 Red Sox.
The Rays threatened for the final time in the eighth, when Pena drew a leadoff walk against Red Sox reliever Manny Delcarmen. Delmon Young then smoked a deep drive that looked like it might carry out and tie the game, but Crisp hauled it in for the first out of the inning. Harris then struck out to bring Jonny Gomes to the plate representing the tying run. Red Sox manager Terry Francona had seen enough and waved his right arm to signal for closer Jonathan Papelbon.
While Gomes had a slugger's chance of tying the score with one swing, he looked overmatched swinging and missing a Papelbon fastball to end the inning. Papelbon then retired the Rays in order in the ninth to record his 30th save of the season.
In losing, the Rays fell to 2-9 on the season against the Red Sox, which is one shy of the total number of defeats for the entire 2006 season. The Rays have lost 10 of their last 13 meetings with the Sox and 12 of 17.