Darrisaw underwent a minor procedure on his core muscle Thursday morning in Philadelphia. This is Darrisaw's second time undergoing surgery since January to repair a groin injury that has limited the first-round pick throughout the offseason and in camp.
"It was taken care of in January," Vikings coach Mike Zimmer said, referencing Darrisaw's first surgery.
"We didn't expect this."
Zimmer reiterated that he did not believe Darrisaw suffered a setback in his limited training camp practices and said the left tackle's movement and change of direction could have caused the aggravated injury.
Darrisaw was absent from Wednesday's joint practice with the Denver Broncos because he was seeing Dr. William Meyers, the founder of the Vincera Institute in Philadelphia, which specializes in the treatment of core muscle injuries.
A source told ESPN that there is optimism Darrisaw will be able to return to practice quickly, though it remains uncertain how much time the rookie will need to get up to speed physically to contend with veteran Rashod Hill for the starting left tackle job.
"I wouldn't put a number on it," offensive coordinator Klint Kubiak said. "With any player coming off an injury, they're all different. I would say when he's been here, he's been really sharp and really dialed in, so mentally I don't think it'll be a problem. We've just got to get his physical reps and get his conditioning."
On Wednesday, Zimmer ruled Darrisaw out of Saturday's preseason opener against Denver. The left tackle has not taken any live team reps in training camp after suiting up for the first time last week. When he has seen the field, Darrisaw has participated only in limited walk-through reps with the second-team unit.
"That's a tough one," Zimmer said last week. "He's one step forward and two steps back.''