''That was a good inning for us,'' Tigers manager Brad Ausmus said. ''I think everyone thoroughly enjoyed it considering the way we had swung the bats in New York.''
Detroit trailed 4-2 entering the ninth against Blue Jays closer Casey Janssen. J.D. Martinez started the inning with a double. After an out, Castellanos homered on a first-pitch curveball. Two pitches later, Suarez gave the Tigers their first lead with a drive to center.
''It was good,'' Castellanos said. ''We really needed that.''
Janssen (3-1) was replaced by Aaron Loup after a two-out double by Ian Kinsler. The blown save was Janssen's third in 21 chances.
''I feel bad for the boys,'' Janssen said. ''We're in a race. Those things burn a little bit more.''
Al Alburquerque (3-1) worked 1 2-3 innings for the win and Joe Nathan finished for his 24th save in 29 chances, getting Josh Thole to foul out with the bases loaded.
Tigers right-hander Anibal Sanchez left in the fifth inning with a strained muscle in his right side. Sanchez will return to Detroit on Saturday for further tests, including an MRI.
''There was no way I could throw another pitch,'' said Sanchez, who was injured on a pickoff throw to first. ''I felt a lot of pain in that moment.''
Left-hander Blaine Hardy took over for Sanchez, who allowed four runs and 10 hits in 4 2-3 innings.
Leading 1-0, Toronto made it 4-0 with a three-run second, thanks in part to a poor defensive inning by Martinez in left field.
Munenori Kawasaki hit a leadoff double on a ball that clanged off Martinez's glove. Kawasaki went to third before scoring on a suicide squeeze bunt by Ryan Goins, who was safe at first when Sanchez fumbled the ball.
After Jose Reyes singled, Goins scored and Reyes went to third when Martinez couldn't make a clean play on Melky Cabrera's ground ball single. Jose Bautista capped it with an RBI single.
Detroit cut the deficit in half on a two-run double by Kinsler in the third.
Blue Jays: First baseman Adam Lind felt tightness in his back following his first rehab game with Toronto's Gulf Coast League team Thursday and did not play Friday. General manager Alex Anthopoulos said Lind remains on track to rejoin the Blue Jays early next week.
Tigers: Outfielder Torii Hunter returned to the lineup for the first time since being hit on the left hand by a pitch from New York's Dellin Betances on Aug. 5. Hunter wore a pad over the batting glove on his swollen hand. Suarez returned for the first time since spraining his left knee sliding into second base on Aug. 4.
Tigers right-hander Max Scherzer will face Blue Jays rookie right-hander Marcus Stroman on Saturday afternoon. Scherzer was a hard-luck loser in his last start, allowing two runs over seven innings in a 2-1 defeat at Yankee Stadium. The loss was just his second in eight starts.
DIRKS' RETURN DELAYED
One day after his rehab assignment was moved from Class-A West Michigan to Triple-A Toledo, the Tigers shut down outfielder Andy Dirks (back surgery) because of a strained left hamstring. Dirks, who will remain in Toledo for treatment, has not played for the Tigers this season.
WE ALL SCREAM FOR ICE CREAM
Hunter said Detroit's veterans were excited by the ninth-inning homers from Castellanos and Suarez, both of whom are in their first full season. ''They had us veteran guys all pumped up and screaming like little kids, like we just got ice cream,'' Hunter said.