The Red Sox (26-11) won two of three games against the Blue Jays (20-18) on their previous visit to the Rogers Centre from April 24-26.
It was the first of three straight series losses at home for the Blue Jays, including dropping two of three this week to the Seattle Mariners, who took the rubber match 9-3 on Thursday.
The Red Sox are coming off a three-game series against their traditional rivals the New York Yankees and they salvaged the finale with a 5-4 victory Thursday night at Yankee Stadium.
Sale has allowed three or fewer runs in each of his eight starts this season. He earned the win April 26 at Toronto when he allowed three runs, four hits and two walks while striking out four in six innings. He is 7-3 with a 2.22 ERA in 13 career games (10 starts) against the Blue Jays. He is 5-1 with a 1.36 ERA in eight games (seven starts) at the Rogers Centre.
Estrada did not allow a run over six innings Sunday in a no-decision against the Tampa Bay Rays, a 2-1 Toronto win at Tropicana Field. But he had allowed four earned runs twice and five earned runs twice in his previous four starts.
Estrada is only one of the Toronto starters who have struggled this season. J.A. Happ, who has been one of their more dependable starters, allowed seven runs in 3 1/3 innings Thursday in the 9-3 loss to the Mariners and has lost two straight outings. Marcus Stroman has yet to win and is 0-5 with a 7.71 ERA.
Another bust this season has been designated hitter Kendrys Morales. He was signed before the 2017 season and was supposed to replace Edwin Encarnacion, who was allowed to leave as a free agent and sign with the Cleveland Indians even though he had said he wanted to remain in Toronto.
Morales was 0-for-3 on Thursday to extend his career-long hitless drought to 0-for-28. He is batting .143 with three homers and 10 RBIs.
"Kendrys is just too good of a hitter to stay where he's at," Blue Jays catcher Russell Martin told the Toronto Star. "Marco is too good of a pitcher. Stroman is the same way. He's going to come around, and when he does it's going to be insane. I like where we're at right now. I really don't like comparing year to year. We have a different team this year. We have some younger players with some new additions to complement our team. I feel like overall we're a better team: more versatile, more depth in a lot of areas, and we do have players that haven't played up to their capabilities yet."
The Blue Jays were 17-21 at the same stage last season.
The Red Sox have had to deal with problems of their own. Left-hander David Price has been diagnosed with a mild form of carpal tunnel syndrome. He was scratched from his scheduled start Wednesday because or swelling in his left wrist. He threw a bullpen session Thursday in New York and has been deemed ready to pitch Saturday in Toronto, the second game of the series against the Blue Jays.
"When I was playing catch in the outfield on the flat ground, trying to throw cutters and curveballs, I didn't have much of a feel for those," Price said. "Those are probably the two I expected to not have the good feel because those are the pitches you really have to put concentrate on putting a lot of pressure on the baseball. But once I got in the bullpen and started throwing off-speed pitches and breaking balls, I felt like it got stronger and it didn't bother me."
Cora said he wanted to see "more rhythm" from Bradley in his at-bats.
"Just being ready," the manager said. "The way I put it, 'Just be an athlete again.' He's one of the best athletes that we have on the team. Get back to being relaxed, moving your hands and get some rhythm."
Bradley is 5-for-50 in his past 16 games with 24 strikeouts and no extra-base hits. He is batting .173 with an OPS of .528.
Boston is 9-9 in the past 18 games after starting the season 17-2.