BOSTON -- Blue Jays reliever Ryan Tepera couldn't believe his eyes when he looked up and saw that he was the winning pitcher - his fifth career victory.
Starter Marcus Stroman was the best pitcher of the game, taking a three-hit shutout into the seventh inning and leaving without allowing an earned run. Dominic Leone relieved him, and was the pitcher of record when Toronto took the lead for good.
But Tepera was awarded the victory by official scorer Bob Ellis, who ruled that Leone didn't deserve it after allowing a game-tying double on the only pitch he threw.
"I thought it was a mistake, but I'll take it," Tepera said, breaking into a laugh after the Blue Jays beat Boston 4-3 on Monday night. "I mean, wins don't really matter as relievers, as long as we win as a team."
Steve Pearce hit a solo homer, then added the go-ahead single in the eighth inning to lead Toronto a victory in the series opener. Stroman shut the Red Sox down for most of the game, but took a no-decision after they scored three unearned runs to tie it in the seventh.
After Andrew Benintendi doubled, Stroman failed to get his foot on the bag when covering first on Jackie Bradley Jr.'s grounder. Christian Vazquez walked to load the bases. Brock Holt's sacrifice fly scored one run, and Mookie Betts singled in another to chase Stroman.
Leone came in, and Dustin Pedroia banged his first and only pitch off the Green Monster. One run scored on the double, and Betts was thrown out at the plate after running through a stop sign from the third base coach.
Tepera (5-1) pitched a perfect eighth. Baseball Rule 9.17 (c) states: "The official scorer shall not credit as the winning pitcher a relief pitcher who is ineffective in a brief appearance, when at least one succeeding relief pitcher pitches effectively in helping his team maintain its lead."
"That's the game of baseball for ya," Leone said. "From Marcus' six innings - that's why baseball is crazy. He deserves that win, no matter what. He pitched his butt off. It's crazy with one pitch the game can switch like that, and the whole win-loss thing kind of gets tossed up for grabs, really."
Toronto went back in front in the eighth when Pearce singled to score pinch-runner Ezequiel Carrera from third.
Roberto Osuna pitched the ninth for his 23rd save.
Heath Hembree (1-3) took the loss.
Betts took responsibility for missing the sign from third base coach Brian Butterfield.
"I didn't even see Butter put up the stop sign. That's my fault for not looking up," Betts said. "I was just thinking, `score.'"
Stroman allowed three unearned runs on five hits and three walks, striking out five. Boston's Eduardo Rodriguez, who was activated from the disabled list (right knee) for the game, allowed three runs on six hits and four walks, striking out eight in 5 1/3 innings.
"I thought with the layoff that Eddie had that was a strong five-plus innings of work here tonight," Red Sox manager John Farrell said.
Home plate umpire Chris Segal remained in the game after getting hit in the head by Josh Donaldson's bat in the first inning. Donaldson, the third batter in the game, swung at a pitch from Rodriguez and lost the handle on his bat. It flew behind him and hit Segal on the top of the head. Segal, who was wearing a mask but no helmet, went back to the ground and remained there until the training staff came running out. After a few minutes, Segal was smiling.
Blue Jays: LHP J.A. Happ (3-6) starts in Game 2 of the series at 7:10 p.m.
Red Sox: Brian Johnson (2-0) is expected to be recalled from Triple-A Pawtucket to make the start.