The Blue Jays dropped to 32-31, while the Orioles improved to 30-30.
Toronto starter Shaun Marcum kept Baltimore off the board until the eighth. He gave up one run on seven hits and walked two in seven-plus innings.
"Marcum pitched great," Blue Jays manager John Gibbons said. "You know what he's all about. He can flat-out pitch."
But on Friday, Marcum's effort was not good enough by itself.
Lefty Brian Tallet replaced Marcum in the eighth, entering the game with a 4-0 advantage. However, Tallet gave up three quick runs. The first came on an RBI single by Nick Markakis. Melvin Mora then belted a 3-1 pitch over the wall in center field to close the gap to one run at 4-3.
Tallet was pulled in favor of Armando Benitez, but the results weren't much different. Benitez (0-1), who took the loss, gave up a solo homer to Kevin Millar. Luke Scott reached on an error by shortstop David Eckstein to set up a two-run homer by Adam Jones.
"I feel sorry for [Marcum]," Benitez said. "He did a great job. They got me today, but we have a new game tomorrow. We have to continue to work hard. That's all it is."
Marcum merely felt bad for the team.
"It's a tough loss and it's frustrating," he said. "We're going to have to bounce back tomorrow. We have great leaders on this team."
On Thursday, Blue Jays closer B.J. Ryan gave up a walk-off homer to finish the Yankees series in New York. He did the same thing in the last Anaheim matchup for the first of two straight blown saves. Toronto came off the road trip with a 4-5 record and was hoping to get back on track at home. It just didn't happen for a bullpen that had been an anchor for the team this year.
"We're playing good baseball," third baseman Scott Rolen said. "Our bullpen has carried us all year, so we're going to try to get back tomorrow and try to win the series."
Orioles starter Brian Burres gave up three runs on five hits over 4 1/3 innings. Lance Cormier surrendered a run in relief before Dennis Sarfate (3-1) took over and got an out to finish the seventh, earning him the win.
Chad Bradford gave up an unearned run in the eighth on a grounder to first base off the bat of pinch-hitter Matt Stairs. Lefty George Sherrill pitched the ninth for his 21st save of the season.
Rod Barajas and Brad Wilkerson each chipped in an RBI single to stake the Blue Jays to a 2-0 lead in the second.
Stephanie J. Geosits is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.