Toronto's starter broke a six-game winless streak and the Blue Jays hit three homers, prolonging the misery of the Red Sox with a 7-5 win on Friday night.
"He was powerful," Toronto manager John Farrell said. "He threw a lot of strikes. He kept the ball on the ground."
The Red Sox were hoping for a boost from their return home after going 1-8 on a West Coast trip that left them just one game ahead of the last-place Blue Jays in the AL East. Now Boston is clinging to fourth place by the very slim margin of .4532 to .4525.
"We're trying to come out and play winning baseball," said Dustin Pedroia, who hit a solo homer. "We haven't played well the last few weeks, basically the last couple of months. We have to find a way to put a good game together and build on it."
The night began poorly as the start of the game was delayed by rain for one hour, 18 minutes.
When it began, Alvarez (8-12) found the right opponent to snap out of the six-game stretch in which he was 0-5 with a 7.67 ERA. He allowed two runs and four hits in 6 1-3 innings. Alvarez left after feeling stiffness in his triceps, but Farrell wasn't concerned.
Red Sox starter Felix Doubront (10-8) also was trying to stop a skid, but now he's 0-4 in his past seven starts after giving up five runs and six hits before leaving with no outs in the fifth.
"It's just unfortunate we can't get anything going in the right direction," Red Sox shortstop Mike Aviles said.
Moises Sierra and Colby Rasmus added two-run homers to help Toronto win its second game after four consecutive losses. Rasmus' 22nd homer of the year in the ninth provided the winning margin when Mauro Gomez hit a two-run shot, his second, for Boston in the bottom of the inning.
"Colby, boy, when he's right, that's as good a swing as you're going to see," Farrell said.
Encarnacion drove in the first two runs with a sacrifice fly in the first inning and his 38th homer in the third on a 1-2 count. Encarnacion tied Adam Dunn of the Chicago White Sox for second most homers in the AL, one behind Texas' Josh Hamilton.
"When you look at what his production has been in a 1-2 count, he's hitting almost .350 on the year with a high number of homers," Farrell said. "He doesn't overswing the bat in those counts."
Sierra made it 4-0 in the fourth with his fourth homer, following a walk to Kelly Johnson.
After Rasmus led off the fifth with a triple, Doubront was replaced by Clayton Mortensen, who gave up a run-scoring single to Yunel Escobar. Then he retired five straight batters, four on strikeouts.
The Red Sox cut the lead to 5-1 in the fifth when Ryan Kalish reached on an infield single, took third on a single by Scott Podsednik and scored when Podsednik was forced out at second on a grounder by Dustin Pedroia.
Boston scored again in the seventh but wasted a chance to do better. With one out, Pedro Ciriaco walked, stole second and scored on a single by Gomez. Podsednik then drove the ball to deep left field where Rajai Davis made the catch. Gomez had rounded second by then and was easily doubled up as he ran back toward first base.
"It was hit better than I thought initially. Then I just tried to outrun it," Davis said. "I saw him sneaking around second base."
Pedroia added his 13th homer, a solo shot, in the eighth.
"We couldn't find a way to get runs early," he said. "We scored some runs late but we need to do a better job of putting some runs on the board."
NOTES: LHP J.A. Happ will miss the rest of the season for Toronto with a fractured right foot. Aaron Laffey (3-5) will start in his place on Saturday night against Daisuke Matsuzaka (1-4). ... Blue Jays C J.P. Arencibia and 3B Brett Lawrie were activated from the disabled list and were in the starting lineup. ... Toronto recalled RHPs David Carpenter and Joel Carreno and C-IF Yan Gomes from Triple-A Las Vegas. ... The U.S. national anthem was sung by Andre McClain, ringmaster of Ringling Brothers & Barnum & Bailey circus. ... Pedroia reached base in all four-at bats — on an error, two forceouts and a homer — and has hits in 29 of his last 31 games.