Gausman allowed two runs and four hits, struck out four and walked none as the Blue Jays completed a three-game sweep with their 16th win in 19 games against the Boston Red Sox this season.
"In a different situation, even if this is two weeks prior, I'm staying in that game," Gausman said. "Obviously, with the postseason coming up, I didn't want it to get any worse."
Gausman said the cut opened up alongside his finger nail in the first inning. He said it only affects him when he throws his split-fingered fastball, a pitch he doesn't throw between starts.
"My other pitches, there's no problem," Gausman said.
To prevent cuts and blisters, Gausman said he routinely treats the area with a laser between starts, and he will continue to do so this week. He's expected to start Game 2 of a wild-card series Saturday.
The win edged the Blue Jays closer to clinching home-field advantage in the wild-card round.
The Jays finish the season with a three-game series in Baltimore against the Orioles starting Monday.
Information from The Associated Press was used in this report.