The win, coupled with the Rangers' loss, allowed the Red Sox (68-51) to take a one-game lead over Texas in the American League Wild Card race.
Buchholz (2-3), who started the year at Triple-A, has had an up-and-down campaign so far, but he was coming off his two best starts of the season, holding both the Yankees and Tigers to two runs.
Unfortunately for Buchholz, Boston's lineup had aces CC Sabathia and Justin Verlander to deal with, and Buchholz and the Sox took two shutout losses. Still, the two games were a positive step for the 25-year-old, who on Wednesday notched his first win since July 17 -- the last time he allowed only one run.
"Confidence has a big thing to do with that," Buchholz said. "The last two games I've pitched prior to this were against two really good ballclubs. [I] didn't come out on top, but still felt good about the outings. Coming into this outing, confidence is good to be high against a team like this."
Francona admired the way Buchholz -- whose name was mentioned in trade rumors for Halladay prior to the July 31 non-waiver Trade Deadline -- used his fastball and changeup to make quick work of the Blue Jays (55-63) early in the game, allowing just one base hit in the first three frames.
But what made the difference for Buchholz was his ability to keep runs off the board when he got into trouble. He allowed three baserunners in the fourth inning before recording the second out of the frame, but he allowed only one run to score. Buchholz found himself in a bases-loaded jam in the sixth, but he got Edwin Encarnacion to fly out to end the threat.
"We've seen in the past where those innings have gotten away," Francona said. "[But] he gathered himself and made a pitch. That's great to see."
With Buchholz keeping six of the seven baserunners he allowed -- six hits, one walk -- from crossing home plate over his six innings, the six runs the Sox put on the board were more than enough for the win.
Designated hitter David Ortiz got things started for Boston, smacking a home run to right field to give Boston a 1-0 edge in the second inning. The slugger has now homered in three straight games for the first time since July 2006, and he's gone deep in four of his past five contests.
Left fielder Jason Bay drilled another home run in the fifth, this one a two-run shot. Bay took a fastball up in the strike zone from Halladay deep to left field just inside the foul pole to give the Sox a 5-1 lead over Toronto. Like Ortiz, Bay has been hot lately, blasting seven homers in his past 11 games.
Halladay (13-6) lasted two more batters after Bay's blast, exiting after only five innings -- his shortest game (excluding injury-shortened outings) since June 14, 2008, a run of 42 starts.
"We made him work for everything and got him out of the game," Francona said. "Sometimes that's the best way to beat somebody like Halladay."
The Red Sox have now hit two or more home runs -- catcher Victor Martinez homered off reliever Brandon League in the ninth on Wednesday for the third Sox long ball of the night -- in five straight games and eight of their past nine, but if any pitcher was going to halt that streak, Halladay was a likely candidate.
"He's human, too, and he's going to give up a bad outing," third baseman Kevin Youkilis said.
It's tough to say who had a better night for the Sox -- the offense or Buchholz.
"It's always fun going up against the other team's best pitcher," Buchholz said. "If you want to succeed in this game for a long time, you've got to succeed against the guys that are the best in the game, and [Halladay]'s definitely in that category.
"It's a confidence booster for everybody."