"We just didn't get anything going today," lamented Mariners manager Eric Wedge as Seattle's season-best four-game winning streak came to a halt.
Most of that was due to Morrow (2-1), who won his second straight start and improved to 3-0 with a 1.89 ERA in three starts against the team that drafted him fifth overall in 2006. The right-hander allowed five hits, walked none and struck out a season-high nine.
"(Morrow's) slider is 89-90," Mariners shortstop Brendan Ryan said. "It's one of the harder sliders you're going to see. When he throws it where he wants to, he pretty much gets the result he wants. That's what you saw with a lot of the right-handed strikeouts."
Millwood, meanwhile, lost his second straight start, allowing three runs, one earned, and seven hits in a season-high seven innings. He walked two and struck out four.
The defeat dropped Millwood (0-2) to 2-8 with a 4.83 ERA in 13 career starts against the Blue Jays. He's 1-6 in nine starts at Rogers Centre, and has not won in Toronto since 2006.
All three runs off Millwood came in the third inning. Yunel Escobar singled and went to third on Kelly Johnson's base hit, then scored when third baseman Kyle Seager couldn't handle Jose Bautista's hard grounder.
"Tough play, I'm not going to fault a guy for that," Millwood said. "That ball was hit hard and you never know what it's going to do on this turf."
Adam Lind followed with a ground-rule double to left and Encarnacion capped the rally with a sacrifice fly.
"I felt like I located the ball pretty well," Millwood said. "Just that one inning kind of got away a little bit but I was still able to keep us in the ball game and go deep into the game. I'm definitely not satisfied by any means but I definitely feel better about it."
As with Millwood, wins against Toronto have been hard to come by for the Mariners, who have lost nine of 11 at Rogers Centre and 13 of their past 19 overall against the Blue Jays.
Morrow set down 10 straight batters after Seager's leadoff double in the second inning, a streak that ended when Michael Saunders hit a one-out double in the fifth. Miguel Olivo reached when Johnson dropped an infield popup, with Saunders taking third on the play, but Morrow escaped by striking out Ryan and getting Chone Figgins to ground out.
"He used all four of his pitches," Blue Jays manager John Farrell said. "As we've seen the last two outings, the late action to his slider particularly, and the power to his fastball, has increased. That's not uncommon for a power pitcher. You're going to see them four weeks into the season really hit stride and that's what has taken place with Brandon."
Encarnacion went 2 for 3 with a double and a sacrifice fly, matching his career-high with five RBIs. Encarnacion's first-pitch drive to right off Hisashi Iwakuma in the eighth was his team-leading sixth home run and his fourth career grand slam.
Morrow was traded to Toronto in December 2009 for RHP Brandon League and OF Johermyn Chavez. ... Lind's third-inning double snapped an 0-for-16 slump against Millwood and was his first extra-base hit since he doubled in a 9-5 win at Kansas City on April 21. ... An MRI of Blue Jays OF Travis Snider's injured right wrist was negative, but he's expected to miss the next seven days to rest after jamming his wrist on a play in the outfield Thursday for Triple-A Las Vegas. ... Seattle LHP Jason Vargas (3-1) faces Toronto RHP Henderson Alvarez (0-2) in Sunday's series finale.