The Vikings are looking to trade veteran center John Sullivan, an NFL source confirmed to the Star Tribune.

Sullivan, 31, has practiced in full and started two preseason games after missing last season due to two back surgeries last fall. He did not play in Sunday's preseason game against the San Diego Chargers so the coaching staff could get a longer look at Joe Berger, per head coach Mike Zimmer.

They must have liked what they saw from the 34-year-old Berger, who started all 17 games last year at center for Sullivan.

Sullivan has started 93 games since the Vikings drafted him in the sixth round (187th overall) in 2008 out of Notre Dame.

The Vikings have to cut their roster to 75 players by tomorrow, although those cuts could be released tonight by the team.

USA Today's Tom Pelissero was first to report that the Vikings were shopping Sullivan.