Travis Snider looked as if he forgot how to run the bases on his first hit and later didn't realize everyone was waiting to talk to him after the game.
Everything must seem new when you've been in the minors for a couple of months.
Toronto scored a run in the first, two in the second and chased John Lackey (5-8) with four in the third.
Snider, who doubled in his first three at-bats, was sent down on April 29 after hitting just .184 in 25 games. It was the first one that had him smiling a few minutes after he realized the media was gathered to see him.
"I think I was so excited I could barely run," said Snider, who stumbled twice rounding first. "I don't know if you saw the baserunning."
Then, before he finished talking, he said: "It's good to be back and see all of your faces."
Blue Jays manager John Farrell felt Snider's dedication to improving his swing showed.
"You could see the work and commitment he made when he went down to Las Vegas," Farrell said. "I think we've seen him get in a much better place to get to balls down over the plate."
Brandon Morrow (5-4), allowed four runs on five hits, walking three and striking out five over five-plus innings on a sunny, humid afternoon. It was his third victory in four starts.
"I started getting worn out," he said of Boston scoring four runs in the fifth after he breezed through the first four innings. "Threw a lot of pitches. I just started falling behind."
The Blue Jays became the latest team to rough up Lackey, who was knocked out after allowing seven runs in 2 1-3 innings. He felt like he couldn't throw the ball where he wanted most of the time.
"Overall, I thought my arm felt pretty good. Just didn't locate well," he said. "I would have fixed it if I had known. Some soft ones fell in on good pitches and made some bad pitches that got hit hard. It kind of all added up to that."
Jacoby Ellsbury had a two-run triple and tied his career best with four hits for Boston, which had its four-game winning streak halted.
Red Sox third baseman Kevin Youkilis left the game in the fourth after getting hit in the upper back. Red Sox manager Terry Francona said he was taken out as a precaution and will be looked at again Tuesday.
Boston rallied early and again late, cutting it to 9-7 with three runs in the eighth, but Frank Francisco got three outs for his 10th save. He struck out Dustin Pedroia, Adrian Gonzalez and Yamaico Navarro with a runner on second.
It was just Francisco's second save in six career chances against Boston.
"Frankie, after a leadoff single, really stepped on it," Farrell said. "To his credit, after falling behind 3-0 to Pedroia, he really came back."
Davis led off the first with a hustle double to left, stole third and scored on the play when Youkilis mishandled catcher Jarrod Saltalamacchia's throw for an error, with the ball bouncing off his glove into foul territory.
Hill opened the second with a homer into the second row of Green Monster seats and John McDonald's RBI single made it 3-0 after Snider doubled.
Then things got really bad for Lackey in the third.
Adam Lind had an RBI single, making it 4-0 after Eric Thames and Jose Bautista singled. Loud boos could be heard echoing around Fenway Park after Lind's hit and again two batters later. Lackey then retired Edwin Encarnacion on a deep drive to left-center before Hill had an RBI single and Snider, the final batter he faced, doubled down the right-field line, making it 7-0.
Lackey, booed loudly as he walked slowly off the mound, was coming off his second best start of the season when he allowed just two runs in 7 2-3 innings in a loss at Philadelphia on Wednesday.
"He left a couple up, especially the last hitter," Francona said. "There was some hard contact. There was some contact that wasn't (hard). They strung them together and they put up a lot of runs."
He gave up seven runs on nine hits in 2 1-3 innings, raising his ERA to 7.47. In seven Fenway starts, he's 3-4 with a 9.17 ERA.
The Red Sox started a comeback, scoring four runs with two outs in the fifth. Ellsbury had his two-run triple, scored on a passed ball by Jose Molina and Gonzalez had an RBI double.
NOTES: Lackey has faced Toronto three times this year, giving up 20 runs in 15 innings for a 12.00 ERA. ... Blue Jays SS McDonald was one player glad to have a road trip to Boston on the Fourth of July. "I'm excited. I'll be sitting on my back porch barbecuing," he said before the game. McDonald lives about 25 minutes from Fenway during the offseason. ... Toronto extended its season high by homering in its 12th straight game. ... The last time the teams met, Boston swept three games in Toronto in June, outscoring the Blue Jays 71-32. ... Francona said LF Carl Crawford, on the DL with a strained left hamstring, may start baserunning soon and RHP Clay Buchholz, on the DL with a strained lower back, won't likely return until after the All-Star break. Buchholz is expected to be re-examined by a doctor in North Carolina later this week. ... Lackey lost his third straight start.