NEW YORK -- James Paxton's injury history was one of the factors that the Yankees strongly considered before agreeing to a big trade this past offseason, yet as they prepare to evaluate the hurler's sore left knee, there is cautious optimism that his early exit will prove to be a minor issue.

Paxton was removed from New York's 6-3 victory over the Twins on Friday evening after throwing 64 pitches over three innings, and the left-hander later revealed that he has been managing discomfort in the knee all season. Paxton is scheduled to undergo an MRI on Saturday morning.

"It's frustrating, but I'm not real worried that it's going to be something long-term," Paxton said. "I think it's going to be a pretty quick fix. I'm looking forward to finding out what's going on so we can treat it and move forward."

Gary Sanchez homered twice and the bullpen combined for six innings of two-run, two-hit ball, striking out seven, though enthusiasm over the victory was tempered by Paxton's departure.

Jonathan Holder took over for Paxton in the fourth inning, with manager Aaron Boone approaching home-plate umpire Rob Drake to allow extra time for an injury substitution. Boone said the Yankees saw Paxton flexing his knee early in the game, but did not think much of it.

"Then we checked on him after that third inning and just decided we didn't want to risk anything too serious because it was bothering him a little bit tonight," Boone said. "It's been something that has been a little bit nagging throughout the year, not a big deal, but tonight was a little more sore consistently."

The discomfort is to the inside of Paxton's left knee, and he said he has been receiving ice and laser treatment on the knee, as well as performing range of motion exercises. Paxton added that the knee has not been a concern prior to this year.

"We've been treating it, managing it, but tonight it was just bothering me to the point where I couldn't keep my direction on the mound," Paxton said. "I was flying open and they didn't want me to overcompensate or hurt something else in the process."

Paxton permitted a run on two hits to the Twins, walking three with a strikeout. His pitches lacked the crispness of the last three outings, during which Paxton tallied 32 strikeouts over 19 2/3 innings.

"It's a dull pain that wasn't allowing me to stay closed," Paxton said. "I was flying open and subconsciously couldn't stay on my back side long enough to keep my direction going toward the plate."

While with the Mariners, Paxton landed on the injured list five times over the last three seasons, but those were for issues with his left elbow, left forearm (twice), left pectoral muscle and lower back. He did miss time in the Minors in 2012 with a right knee injury, though Paxton said that bears no resemblance to what he currently is feeling.

Through seven starts for the Yankees, Paxton is 3-2 with a 3.11 ERA, allowing 32 hits while striking out 52 against 13 walks in 37 2/3 innings. Including Friday, the Yankees have won each of Paxton's last four starts, and he is 2-0 with a 1.19 ERA over that span.

"He's an awesome pitcher, one of our best guys," reliever Adam Ottavino said. "Right now, we don't know what it is. In my mind, it'll be a little blip and then he'll be back out there throwing the way he does for us. Obviously we can't afford to lose him for too long, but at this point I think we're kind of used to it. We'll see."