John Carlson is making up for lost time with the Minnesota Vikings. The problem is, he doesn't have much left.

The tight end sprained the MCL in his knee on July 31 and just returned to practice Sunday, two weeks before the season starts.

The Vikings signed the free agent during the offseason to fill the void left by Jimmy Kleinsasser's retirement and Visanthe Shiancoe's departure to New England. They are counting on Carlson to be a big weapon (along with Kyle Rudolph) in their two tight-end sets.

Suffice it to say, Carlson has a lot of catching up to do.

“I haven’t run a whole lot in the last few weeks,” he said. “My conditioning level isn’t where it needs to be yet. But I have a couple weeks before that first game and I will do what I can to get back to where I need to be.”

Carlson attended his first light practice on Sunday and said his knee felt fine afterward, but he was looking ahead to Monday afternoon's practice in full pads for a longer duration. So was his offensive coordinator, Bill Musgrave.

“We’re going to find that out (how ready Carlson is) this week and next,” Musgrave said. “[Sunday] was his first day. He was feeling his way a little bit and understandably so, but we will get him out there [Monday] and hope it is better.”

Carlson said he watched practices and studied the offense during his absence, but nothing makes up for physical reps.

“Communicating with the tackle, seeing, reading coverages, running the correct route, making the correct adjustments -- I need to get that really quickly, but it will come,” he said.

Musgrave said Carlson’s veteran experience is a strength that helps him against NFL coverages, and “he has quickness and suddenness to win versus man coverage as well.”

The Vikings hope that experience will come into play soon.

For more Vikings news and notes, follow Joe Oberle on Twitter @CBSSportsNFLMIN.