Keane made his first senior start for the Red Devils in Oslo, playing a full 90 minutes in which neither side managed to break the deadlock.
The 19-year-old defender's performance at left-back caught the eye of Vidic, who played in central defence.
"I'm glad he's had a full ninety minutes," Vidic told MUTV. "He was confident on the ball and it's a big change from the youth academy, obviously, and I think he did really well."
United's next pre-season friendly is against Barcelona on Tuesday.