Morrow and two relievers combined on a five-hitter, pitching the Toronto Blue Jays to a 6-0 victory on Thursday night that trimmed New York's lead in the tight AL East.
Morrow (9-7) scattered four hits over seven innings, walked three and struck out three to win for the first time in five starts. Even though his fastball was a few mph slower than normal, the right-hander kept the Yankees off balance by varying his pitch selection.
"We stayed with a good mix of everything all night, tried to keep them off balance and not fall into any patterns," Morrow said.
The assortment of off-speed pitches proved to be a problem for the Yankees, held scoreless for the sixth time this season.
"It didn't seem like he was really raring back tonight," New York's Nick Swisher said of Morrow. "It felt like he was pitching. He was throwing a lot more cutters than I remember, a lot more changeups, breaking balls, things like that, rather than that flat 96 (mph). He did a good job."
Yankees catcher Russell Martin said Morrow was aggressive in the strike zone.
"Every time you're in there it feels like you're behind in the count," Martin said. "He was just getting strike one really early and mixing his pitches."
It was Morrow's longest outing since returning from the disabled list Aug. 25 after missing 65 games with a strained muscle in his left side.
"You always want to try and finish up strong," Morrow said. "It takes a little while to get back into a groove (after an injury), but I've felt good the whole time."
Edwin Encarnacion had three hits and three RBIs. Brett Lawrie hit a two-run homer and J.P. Arencibia added a solo shot as the Blue Jays handed an assist to idle Baltimore, shaving New York's division lead over the Orioles to one game.
The Yankees lost for the third time in five games and wasted a chance to go two up with six to play.
"We know what's at stake right now and we've just got to go out there and keep picking up wins," Swisher said. "We've got a little six-game playoff race."
Making his third start since missing 14 games with a sore right shoulder, New York right-hander Ivan Nova (12-8) allowed four runs and six hits in 4 2/3 innings. He walked two and struck out four.
"I'm not pitching the way I want and I'm not getting the result I want, so that's not good," Nova said.
Knocked out in the third inning of his previous start, Nova has not won back-to-back outings since a five-start winning streak from May 25 to June 17. The 87 extra-base hits off him are the most yielded by any big league pitcher.
"He just hasn't had the command; that's the bottom line," Yankees manager Joe Girardi said.
Morrow got some help from his defense after Robinson Cano's one-out single in the fourth. Rookie left fielder Anthony Gose crashed into the wall to haul in a deep drive from Swisher, then threw the ball into second baseman Kelly Johnson, who doubled off Cano at first.
"(Cano) probably got a little bit too far, but it's a great play by Gose," Girardi said.
Nova ran into trouble after walking Gose to begin the fourth. Lawrie followed with an opposite-field homer to right, his 10th of the season and first since July 22.
Gose led off with a single in the fifth, went to second on Lawrie's groundout and moved to third on a bunt single by Colby Rasmus. That brought up Encarnacion, who drove in both runners with a double into the right-field corner.
Even with the infield drawn in, New York couldn't stop Toronto from making it 5-0 against Derek Lowe in the seventh when Lawrie scored on Encarnacion's grounder to shortstop. Arencibia capped the scoring with a second-deck homer off David Aardsma in the eighth, his 18th.
Blue Jays shortstop Yunel Escobar was greeted with a smattering of boos in his first home game since wearing eye-black with an anti-gay slur. A few fans booed when Escobar's name was announced as the lineups were read before the game. There was a mix of boos and cheers as Escobar batted in the bottom of the first, lining out on Nova's first pitch.
"The three years I've been here in Toronto, the fans have been great to me," Escobar said through a translator. "They know how hard I work and I give everything on the field. I made a mistake. I'm sorry for it."
Escobar's subsequent at-bats drew almost no reaction from the crowd of 23,060.
Yankees 3B Alex Rodriguez, who did not play in Wednesday's victory at Minnesota, started at DH. Jayson Nix was at third base. Girardi said Rodriguez could return to third base during this series, possibly Friday. Rodriguez went 0 for 2 and has one hit in his last 16 at-bats. ... Aardsma pitched in a major league game for the first time since Sept. 19, 2010. He missed the past two seasons following hip and elbow operations.