"He's a little bit of a bulldog, he's scared of nothing," Melvin said of Gray, noting the right-hander's experience on the big stage just last Saturday.
Melvin said he doesn't know how he might use, if at all, 18-game winner Colon, who is "willing to do anything."
"I'm not really sure how I'm going to handle that yet," Melvin said.
The Tigers will counter with Justin Verlander, who also pitched in the decisive Game 5 of the ALDS against the A's last year, throwing a four-hit shutout.
"Well, you don't pretend. It's not just another game," Verlander said after the Tigers evened the series with an 8-6 win Tuesday at Comerica Park. "The season is on the line. It was on the line for us tonight, too. This whole season, the way we battled and played as a team, comes down to one game, may the best team win. You can't treat it just like another game. It's a little bit different. There is more to it."
Verlander dominated in a thrilling pitcher's duel with Gray on Friday, though he had nothing to show for it in a 1-0 loss.
Verlander is riding a 22-inning postseason scoreless streak against the A's, and has 33 strikeouts over the past three playoff matchups with Oakland, 11 in each outing.
Not that the A's are counting.
"He's been beaten before, it can happen again," third baseman Josh Donaldson said.
The AL West champion A's know what's at stake -- and realize full well the challenge of facing Verlander again. Last fall's frustrating finish is still fresh for everybody.
"Going to go out there like we always do," leadoff hitter and center fielder Coco Crisp said. "He's a great competitor and we're a competitive team. We're going out there to go out and beat him."
Gray allowed four hits in eight shutout innings in Game 2, striking out nine and walking two in a no-decision.
If he wins on Thursday night, he would be the first rookie pitcher to win two games as a starter in a single division series since Jaret Wright did it with the Cleveland Indians in 1997, according to Elias Sports Bureau.
Information from The Associated Press was used in this report.