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TORONTO -- Alfredo Aceves had a message for his manager after Boston's 0-3 start: Keep trusting in us, and it'll all work out.

Monday night in Toronto, Aceves showed exactly what he meant.

Ryan Sweeney singled home the go-ahead run and the Red Sox rallied for three runs in the ninth inning to beat the Blue Jays 4-2 on Monday, spoiling Toronto's home opener and avoiding the first back-to-back 0-4 starts in team history.

"What a great effort by a whole group of guys out there tonight," manager Bobby Valentine said.

Seeking to lift his skipper's spirits after he had coughed up the lead Sunday in the finale of a season-opening sweep at the hands of Detroit, Aceves penned a message of support to Valentine before Monday's game.

"He wrote me a little note," Valentine said. "It talked about trust. I told him I trusted him. He knew he was going to have the ball."

Aceves said the message was a simple one.

"I just said 'trust,'" he said. "We've still got to trust, you know? It's been like three games and everything was negative. But we stick together and one of those things is trust."

Dustin Pedroia homered and scored the tying run as the Red Sox handed new Blue Jays closer Sergio Santos his second blown save in three appearances.

"We had a couple of tough ones in Detroit but we're going to bounce back and play as hard as we can every single night," Pedroia said.

Handed a 2-1 lead to start the ninth, Santos (0-1) surrendered a leadoff double to Pedroia, who advanced to third on a passed ball and scored on a sacrifice fly by Adrian Gonzalez.

"Adrian has shown me in a short time that he's as good as there is in the game," Valentine said.

Kevin Youkilis struck out before David Ortiz and Cody Ross drew consecutive walks. After a visit to the mound by pitching coach Bruce Walton, Sweeney hit an RBI single through the right side.

Darnell McDonald, pinch-running for Ortiz, slid home safely when Blue Jays catcher J.P. Arencibia couldn't handle the throw from Jose Bautista, a miscue that also allowed both runners to advance. Ross scored soon after when Santos uncorked a wild pitch that bounced into Boston's dugout along the first base line.

Making his first home appearance since being acquired in a December trade with the White Sox, Santos was booed off the mound by the crowd of 48,473 when manager John Farrell came out to replace him with Luis Perez, who ended the inning by getting Mike Aviles to ground into a fielder's choice.

"I'd be booing too," Santos said. "It wasn't pretty."

Scott Atchison (1-0) worked three shutout innings for his first win since July 23, 2010, and Aceves closed it out with a perfect ninth for his first save, rebounding after failing to retire a batter in his two previous outings this season.

"His breaking ball was really good, his fastball was crisp," Valentine said.

After making a diving catch to rob Jarrod Saltalamacchia of a hit in the top of the third, center fielder Colby Rasmus got Toronto's offense started in the bottom half, hitting a one-out triple up the alley in right center. Yunel Escobar walked before Rasmus scored on Kelly Johnson's fielder's choice grounder to the mound, sliding in just ahead of Saltalamacchia's swipe tag.

Bautista flied out before Edwin Encarnacion doubled Toronto's lead with an RBI single to left.

Blue Jays right-hander Henderson Alvarez kept the Red Sox off the board until the sixth, when Pedroia hit a solo home run to left center, his first.

"He's got great stuff," Pedroia said of Alvarez. "His two-seam fastball is pretty darn good. He's going to be really good for a long time. I wish he wasn't in our division."

The homer was the only run allowed by Alvarez, who gave up four hits in six innings, walked one and struck out a pair.

Making his fourth career start, and his first since July 16, 2010, Red Sox left-hander Felix Doubront allowed two runs and four hits in five innings. He walked three and struck out a career-high six.

Game notes

The Blue Jays are 26-10 in home openers, but have lost two of the past three. ... Valentine tweaked his lineup by putting Youkilis in the cleanup spot, between Gonzalez and Ortiz. ... Toronto OF Travis Snider, currently at Triple-A Las Vegas, has been held out of the lineup for precautionary reasons the past two days after jamming a finger diving back into first base. ... In an effort to avoid crowd control problems, the Blue Jays limited beer sales in the upper deck to one per customer, per trip -- half the amount permitted at regular games. Concession stands elsewhere in the stadium were not affected. Ironically, fans in the lower levels threw debris on the field in the third inning, and were seen fighting in the fifth.