The season has since taken a turn for the worse for both.
Buehrle looks to end his winless slide Friday night when Toronto visits the Tampa Bay Rays.
The Blue Jays (48-45) were 38-24 with a six-game lead after June 6, with 14 games separating them and the last-place Rays. They've since gone 10-21 and have been overtaken by Baltimore, while Tampa Bay has closed within 6 1/2 games of Toronto.
Buehrle (10-6, 2.60 ERA) led baseball with 10 victories after June 1, but is 0-5 in six starts since. However, the left-hander has also received just 10 runs of support over 40 innings since his last win.
He recorded victories in two earlier matchups with Tampa Bay, limiting them to three earned runs over 15 1-3 innings. He was one out shy of a shutout and struck out a season-high 11 in a 3-0 win in his season debut at Tropicana Field on April 2.
Toronto tallied 10 runs during a 1-5 stretch prior to Wednesday, but even a better offensive showing couldn't prevent an 8-7 defeat to the Angels. Reliever Aaron Loup gave up the go-ahead homer to Albert Pujols in the seventh inning after not allowing a home run in 59 straight relief appearances.
"We (gave) away a good opportunity tonight," manager John Gibbons told MLB's official website. "We had the lead, coughed it up, took a slim lead. It was disappointing, it really was."
Tampa Bay (42-52) has won 11 of 15, though it was 3 for 18 with runners in scoring position while dropping two of three to Kansas City. The Rays were 1 for 9 with runners in scoring position in Wednesday's 5-4 loss and Kirby Yates surrendered a three-run homer to Salvador Perez in the ninth.
"I understand we lost by a run on a three-run homer in the ninth inning," manager Joe Maddon said. "But we left a lot of chicken on the bone and you just can't do that stuff."
Desmond Jennings was 0 for 11 in the series after going 12 for 28 in his previous six contests, but he's 7 for 18 against Buehrle.
Chris Archer (5-5, 3.16) takes the mound for Tampa Bay having pitched at least seven innings in three straight starts. He beat Detroit 7-2 on Saturday, yielding both runs on solo homers over a season-best 8 1-3 innings.
"It was my best game so far (this season)," Archer told MLB's official website. "... But there is room to grow. I'm going to continue to execute pitches better."
Archer is 2-0 with a 2.22 ERA in five career starts versus the Blue Jays and beat them 7-2 on April 3, yielding two runs in six innings.
Toronto won five of the teams' first seven meetings this season with Adam Lind going 6 for 14 with two home runs in five games. Lind, though, was placed on the 15-day disabled list Friday with a broken right foot.
Matt Joyce was 9 for 18 with five doubles.