TORONTO -- Joba Chamberlain pulled on his uniform pants Friday afternoon knowing he would have absolutely no chance to win this game. By the ninth inning, Roy Halladay had forced the Yankees to acknowledge the same thing.

While Chamberlain struggled in another rule-shortened effort, the Blue Jays' ace had no difficulty finishing what he started, whipping a complete-game one-hitter to best the Bombers, 6-0, and snap New York's seven-game winning streak.

"When you're going against Doc, you know you've got to be that much better," Chamberlain said. "And, obviously, I wasn't that good."

Handcuffed to a sixth-inning double by light-hitting backup infielder Ramiro Pena but coasting securely atop the American League East, the Yankees weren't doing too much hand-wringing about the outcome. But there are legitimate concerns about Chamberlain, who was indeed less than impressive.

Making another abbreviated start under the revised "Joba Rules," Chamberlain hurled just three innings, burning through 59 pitches as the Blue Jays touched him for three runs -- two earned -- on six hits, as the right-hander walked two and struck out two. There are no further alterations in store.

"This is what we're going to stick to," Yankees manager Joe Girardi said. "I thought he was aggressive with his fastball tonight and did the things that we wanted. Unfortunately, we didn't score any runs tonight, and Halladay was outstanding."

Chamberlain's defense didn't do him any favors in the first inning, as Aaron Hill and Adam Lind stroked back-to-back doubles by taking advantage of Eric Hinske in right field. Hill scored on a Pena error that scooted through his legs on the unfamiliar artificial turf.

Vernon Wells was hit by a pitch to open the third inning as Chamberlain labored through a 20-pitch frame, watching the third run come home on a Joe Inglett single. That would be all for Chamberlain, who knew he was limited to three innings and thought the start represented some level of progress.

"When it comes down to it, those three innings should have been a little bit better," Chamberlain said. "Maybe I should have given up one run. That's something I've got to build off for next time and continue to get the ball to try and go out and help the team win."

Johnny Damon said that the revised plans still can't be a ideal situation to play under.

"He's going out there and the only option is to possibly lose a game," Damon said. "He's got no chance to win a game. It's got to be tough and frustrating, but it's something we have to do right now."

The contrast was even more striking given that Halladay retired the first 14 Yankees he faced before Jorge Posada worked a two-out walk in the fifth inning, breaking up the perfect-game bid.

Pena logged the first Yankees hit with one out in the sixth, lining a double to right field to break up Halladay's no-hitter. Nicknamed "El Nino," Pena said the hit was bittersweet and that he couldn't be happy because New York lost the game.

"You just try to make contact, you know?" Pena said. "I know that he's pitching without hits, so I just tried to get a good pitch. He threw me a curveball, and it stayed there. I hit it."

New York had its best chance to put a run across in that inning, as Hinske and Mark Teixeira worked two of Halladay's three walks. But Alex Rodriguez struck out looking to end the inning, and no Yankees hitter reached base the rest of the way as Halladay continued carving in a nine-strikeout performance.

"He put it all together tonight," Damon said. "I don't think there were too many pitches over the heart of the plate that he left there for us. He threw his changeup a lot more -- he threw it to me about 10 times. His curveball he kept down, and the way he works and the way he pitches ... he did such a great job."

Girardi knew he would have to lean heavily on his bullpen and did so, using each one of the Yankees' September callups in relief. Mark Melancon hurled two innings of one-run relief, and Jonathan Albaladejo fired a scoreless sixth inning before Mike Dunn was charged with two runs in his Major League debut, with Edwar Ramirez inheriting a bases-loaded jam in the seventh and allowing a two-run double to Hill.

After the game, Girardi said that he thought there were good signs out of the small body of work from Chamberlain, spotting improvements in his command, sharpness and attacking of the strike zone.

Ultimately, the Yankees' plan is that Chamberlain will be built back up and be capable to throw 100 to 110 pitches by the end of September, when the danger area of his innings limit will have passed and the postseason rotation will need to be considered.

"What we're doing right now is not going to last forever," Girardi said.

Girardi refused to discuss the playoffs in detail on Friday, but when pressed, he acknowledged that the Yankees will need four starters if they are able to reach a seven-game playoff series.

Should the Yankees be enjoying an appearance in the AL Championship Series, Chamberlain's number will almost certainly be called, unless Sergio Mitre or Chad Gaudin do a great deal to inspire confidence. Unflapped, Chamberlain vowed that he will be prepared by then.

"We've still got a month left," Chamberlain said. "That's a lot of baseball to be played and be learned. That's the greatest thing about this. We are coming around to the end, but there is a lot of time to get everything going. I'm not far off, and I know that."