"Guys are getting good at-bats," Zaun said. "We don't have a Sosa, McGwire or even a Delgado anymore, but two guys like Hillenbrand and Koskie could hit 25 a piece to make up for that."
After 12 seasons and 336 home runs for Toronto, Delgado signed with Florida as a free agent in the offseason.
Wells, Koskie and Hillenbrand each homered to left off David Wells for Toronto's first back-to-back-to-back homers since 2001.
"You thought (Wells) would be able to come back and make that adjustment (after the first home run)," Boston interim manager Brad Mills said. "But I have to tip my hat to him, he really made some adjustments after and pitched well."
The Red Sox dropped to 2-1 since Terry Francona was hospitalized Wednesday after experiencing chest pains. He is expected to return for Monday's home opener at Fenway Park, when the Red Sox receive their World Series rings.
David Wells (0-2) struggled in his second straight start, giving up six runs in 6 1/3 innings. He was also hit hard on opening day against the New York Yankees, allowing 10 hits and four runs in 4 1/3 innings.
"If you dont make the pitches thats what happens -- you give up runs," said Wells, who has a 8.44 ERA this season. "Youve got to get the bad ones out of the way, I guess."
Zaun hit his first home run of the season off reliever Blaine Neal over the right-field fence to help the Blue Jays bounce back from a series-opening loss Friday.
"I got a pitch up in the strike zone and I was waiting for it. Ive started to learn that the less greedy I am, the better off I am," said Zaun, who was 2-for-4 with five RBIs.
Dave Ortiz pulled Boston to 5-4 with his second homer, a three-run shot off Roy Halladay in the sixth.
Halladay was having a solid outing until Ortizs homer, and ended up allowing five runs and seven hits in six-plus innings.
"I left the ball over the plate, but other than that I felt pretty good about it," Halladay said. "Its tough to come back and score runs but we did and got a big win."
The Red Sox tied it at 5 in the seventh on a close play at second base. Halladay was pulled after Jay Paytons leadoff single. Reliever Scott Schoeneweis loaded the bases, then got Trot Nixon to ground into a potential inning-ending double play but Blue Jays first baseman Eric Hinskes throw to second pulled shortstop John McDonald off the bag.
Mark Bellhorn slid safely into second and Payton scored the tying run. Toronto manager John Gibbons came out to argue.
The Blue Jays opened the scoring with a pair of runs in the second inning. Koskie scored on Hinske's grounder, and Zauns single scored Hillenbrand.
Nixon broke out of a 1-for-11 slump with a RBI single in the third, scoring Ramon Vazquez.
- LHP Ted Lilly (shoulder) is scheduled to start Sunday, marking his first appearance of the season.