TORONTO _ Three weeks away from being the Yankees' probable starter in the best-of-five AL Division Series opener, Masahiro Tanaka went to work against the fourth-place Blue Jays.
Tanaka has at least two more starts to refine his arsenal before October.
And his last two starts have not been sharp efforts, including Friday night's no-decision at Rogers Centre.
On Friday night, Tanaka went five innings and handed the bullpen a one-run lead.
But Adam Ottavino balked in the tying run in the seventh.
The game dragged into the 12th, when Bo Bichette drilled a leadoff, game-winning home run off lefty Tyler Lyons to seal a 6-5 Blue Jays win before 23,915 fans.
The Yankees' magic number to clinch the AL East remained at five, pending the Rays' late outcome against the Angels at Anaheim.
In the 10th inning, Blue Jays lefty reliever exited with what appeared to be a devastating elbow injury.
After walking Did Gregorius to lead off the inning, Tim Mayza uncorked a pitch to Cameron Maybin that flew to the backstop near the opposite on deck circle.
Mayza crumpled to the mound in pain, protecting his left arm as infielders and catcher Reese McGuire rushed out, along with Toronto's medical staff.
After a few minutes, Mayza walked off with his left arm stiff at his side. Initially, the Blue Jays would only say that Mayza suffered a left elbow injury and was being evaluated by medical staff.
Ryan Tepera replaced him and finished the inning.
Tanaka was charged with four runs on eight hits with no walks and six strikeouts.
He gave up a solo home to Randal Grichuk in the second inning and two more runs scored with two out in the fourth, on an RBI double by Reese McGuire and an RBI single by Teoscar Hernandez.
The Yankees scored five times in the fifth to take a 5-3 lead but Tanaka handed back one run in Toronto's fifth on a double by Bichette and an RBI single by Cavan Biggio to open the inning.
In the ninth, with Blue Jays at the corners, Luis Cessa got Vladimir Guerrero Jr. to hit into an inning-ending double play, started by shortstop Didi Gregorius, to force extra innings.
Over his last two starts, Tanaka has yielded eight runs in nine innings at Boston and Toronto.
And his last victory came at Seattle on Aug. 27, when he threw seven shutout innings against the last-place Mariners.
Manager Aaron Boone has hinted at some postseason pitching decisions, such as the possibility of using CC Sabathia out of the bullpen or hooking Domingo German to his start in a tandem outing.
The Yankees tried that successfully in Thursday's doubleheader nightcap victory at Detroit and they're set to try it again at Yankee Stadium on Wednesday night against the Angels.
But overall as a staff, Boone said hey really haven't spoken about an October rotation with much depth of focus.
"That's probably something we'll start to get into a lot on this coming homestand," Boone said, with the Yankees magic number still a five.
A combination of five Yankees wins and/or Tampa Bay Rays losses would give the Yanks their first AL East title since 2012.
On Friday night, the Rays played a late game against the Angels at Anaheim.
Boone's postseason pitching also depends on the opponent, with the Athletics, Rays and Indians jockeying down the stretch for the chance to play in the single elimination wild-card game.
But there shouldn't be much guesswork about Tanaka as the Game 1 starter, though Tanaka needs to refine his arsenal and his mechanics before then.
