It's Lester who has been far better of late, and the Blue Jays are likely happy his outstanding recent run with the Red Sox has led to his being scratched from Wednesday night's meeting as trade rumors swirl.
Buehrle has been anything but impressive, and given Lester's recent success, Blue Jays hitters should prefer replacement Brandon Workman as they go for a second straight three-game sweep at Fenway Park.
The Boston ace has done nothing but increase his value in recent starts, leading the Red Sox (48-59) to announce after Tuesday's 4-2 loss that Lester wouldn't make his scheduled turn in the rotation with Thursday's trade deadline looming.
"In light of all the uncertainty surrounding Jon Lester, it's probably in everyone's best interest that he does not make that start," manager John Farrell said.
The decision might have been made easier with the Red Sox having now lost seven of eight by a 50-17 margin.
"Obviously we're not in the position that we want to be in," Dustin Pedroia said. "We haven't played very well and our record shows that."
Workman (1-3, 4.13 ERA), who will be recalled from Triple-A Pawtucket, lost his last three big league starts before being sent down on July 8. He's 1-3 with a 4.50 ERA in eight starts this season and has only faced Toronto in a 2013 relief appearance.
While Lester's 10-7 record includes a 4-0 mark and 1.07 ERA in eight starts since last being tagged with a loss on June 7, Buehrle (10-7, 3.19) has gone nearly two months without a victory after a 10-1 start.
Since last winning on June 1, the left-hander is 0-6 with a 4.83 ERA in nine outings. His latest was unquestionably his worst of the year, as Buehrle surrendered six runs and nine hits with a pair of home runs in just three innings of Friday's 6-4 road loss to the New York Yankees.
"I don't feel like I've thrown (bad enough) not to get a win in the last two months," Buehrle told MLB's official website. "Obviously these last couple of outings, I have, I've pretty much tanked. But before that, I felt like I was throwing pretty good.
"I think the ball's not going to guys, it's finding holes now. When you're going lucky, when you're going good, those balls go to your defensive guys."
The one loss he suffered during his impressive start was to Boston on April 25. He's 1-1 with a 5.84 ERA in two starts against the Red Sox this season. At Fenway Park, he's 2-0 with a 2.77 ERA in four starts since joining Toronto prior to the 2013 season.
Pedroia is 15 for 40 (.375) against Buehrle while David Ortiz is 25 for 79 (.316) with 13 extra-base hits.
The Blue Jays (58-50) have owned the season series, winning five straight, all five contests in Boston and nine of 12 overall. They're also 9-3 since the All-Star break with four straight wins to get within 2 1/2 games of Baltimore for the AL East lead.
Despite the absence of Brett Lawrie, Edwin Encarnacion and Adam Lind, Toronto has had no shortage of offense with a .324 average and 6.18 runs per game over its last 11.
Melky Cabrera is batting .388 in 12 games against Boston this season while Jose Bautista isn't far behind at .362.
Red Sox first baseman Mike Napoli was out of the lineup Tuesday due to swelling on the ring finger of his left hand.