KANSAS CITY, Mo. -- Whit Merrifield was not thinking he never had a walk-off hit when he dug in at the plate in the ninth.

Merrifield delivered his first career walk-off hit with a two-run double as the Kansas City Royals rallied from a four-run deficit to top the Toronto Blue Jays 5-4 on Friday night.

All four runs in the ninth inning were scored with two outs.

"The tying run is on third, just hit the ball hard and if it happens to get in the gap or over the fence, that's a bonus," Merrifield said of what he was thinking. "In that situation, you're just trying to get that run in from third."

Merrifield doubled with one out in the eighth, but did not score.

"I felt like I had good at-bats all night, so it was nice to come through when it mattered," he said.

He was the seventh man to bat in the ninth.

"I counted out in my head if it worked out, I was going to get to hit and I had confidence in our guys to get the job done and they did," Merrifield said. "I had a chance and took advantage of it."

Alcides Escobar singled home Salvador Perez with the first run of the inning and Alex Gordon singled home Brandon Moss, who had walked, with the second run.

"I had him (Moss) 1-2," Toronto reliever Ryan Tepera said. "Just kept battling and battling. Mixed it up with a fastball and a slider, and he just kept battling and we ended up walking him. That was the key point of the inning really."

Merrifield greeted Jason Grilli with a double to left to score Escobar and Gordon.

"I was just hoping Salvy was not going to run out on the field too soon," Moss said. "Esky scored and Salvy was already on his way out and I said, 'wait, wait, wait. We gotta make sure Gordy gets around, too.' That was a great at-bat by him. He got a pitch and didn't miss it."

The victory moved the Royals (36-36) to .500 for the first time since they were 6-6 on April 16.

Joakim Soria (4-2) got the victory and Aaron Loup (2-1) took the loss.

Blue Jays left-hander J.A. Happ limited the Royals to four hits and one run in 6 2/3 innings while striking out five and walking none. He left with a 2-1 lead.

"The bullpen's been great for us," Happ said. "This shouldn't be an issue. This was just one of those nights and it didn't go our way, but we're going to have to bounce back."

Troy Tulowitzki doubled home Kendrys Morales with the first Toronto run in the fourth inning and scored on a Jake Junis wild pitch.

Toronto added two runs in the ninth with run-producing singles by Josh Donaldson and Justin Smoak.

The Royals chased Happ in the seventh, which Lorenzo Cain led off with a double. Eric Hosmer reached on Ryan Goins' fielding error. Perez laced a single to left, scoring Cain with still nobody out.

Happ rebounded to retire Mike Moustakas on an infield pop-up and struck out Moss. Danny Barnes was brought in to face Escobar, who flied out to center.

"Just getting ahead, getting strike one," Happ said. "I feel like I've been getting better at that. That helps me control the count a lot better and be able to throw the other pitches off of that. So, that was a plus tonight."

"Just trying to stay out of the middle as much as I can and just trying to stick that ball to each side and just use everything. I feel like Russ did a good job back there tonight, kind of being on point with what we wanted to do. And, I feel like it is getting better."

Royals rookie Junis was pulled after 6 1/3 innings, allowing two runs, six hits and two walks while striking out four.

The Blue Jays scored two runs on one hit, a hit batter and a wild pitch in the fourth inning.

Junis hit Morales with a pitch to start the inning. Tulowitzki doubled to the right-center gap, scoring Morales. Dwight Smith Jr. flied out to deep center to get Tulowitzki to third. After walking Kevin Pillar, Junis uncorked a wild pitch with Goins batting, allowing Tulowitzki to score.

Happ retired the first 10 batters he faced before Jorge Bonifacio doubled to left with one out in the fourth, but he was stranded at third base.

The only other Kansas City baserunner the first five innings was Moss' opposite-field single with two out in the fifth.

Jose Bautista and Russell Martin singled with two outs in the third, but Junis struck out Donaldson to end the inning.

NOTES: The Royals designated for assignment RHP Chris Young, who had a 7.50 ERA and was allowing opponents to hit .353. They added RHP Neftali Feliz, who was released by the Brewers after going 1-5 with eight saves and a 6.00 ERA. ... The Blue Jays brought up OF Ian Parmley from Triple-A Buffalo and he started in right field. RHP Cesar Valdez was sent to the Bisons. ... OF Steve Pearce was not in the Toronto lineup for the second straight day with a bruised right knee. ... Royals LHP Danny Duffy will begin a rehab assignment Saturday with Triple-A Omaha. Duffy is on the disabled list with a strained oblique. ... Blue Jays RHP Marco Estrada and Royals LHP Jason Vargas are the Saturday probables.