Marquis (12-6, 3.49 ERA), tied with the Giants' Matt Cain for the National League lead in victories, was supposed to square off against Cain on Friday night. But the blister problem, which flared after a start against the Mariners on June 13, forced the Rockies to delay him.
In his last start, when he went eight innings and beat the Padres, 6-1, on July 19, he changed his grip because the blister affected him on his sinker and changeup, which account for about 60-75 percent of his pitches in a given game.
"The big thing with me is as long as I don't have to alter my mechanics and take away from my pitches, that's what I'm looking for," Marquis said. "The way it felt, can I say it's 100 percent? No, it's not 100 percent.
"But I threw my sinker for the first time in two weeks with my normal grip. So that's a good sign. I've still got two days, but I'm ready to go physically, and we'll take it from there, start-by-start."
Marquis threw the session with gauze covering the finger, something he is not allowed to use in a game. But he pointed out that he's thrown bullpen sessions with the finger covered before and not felt as good as Sunday.
Marquis, 30, was born in Manhasset, N.Y., grew up in the area and has an offseason home there. Starts in the Big Apple remain special to him.
"It's where I'm raising my family right now," Marquis said. "To be around family and friends who have been behind me for 30 years now, it's nice to sleep in your own bed and be in your own neighborhood."
Thomas Harding is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.