Mark Sanchez and Hayden Panettiere
National Photo Group
05/31/2011 at 03:00 PM EDT
may have just split with with Ukrainian boxer
Wladimir Klitschko – but the petite Scream 4
actress was spotted in Malibu over the Memorial Day weekend with New York Jets quarterback Mark Sanchez
. On Monday, the two stepped out for a bite at an In-n-Out Burger with friends.
So, are they more than just burger buddies?
"They're not dating at all," a source tells PEOPLE. "They're really just friends."
Another source tells PEOPLE that they've been spotted together for months – but maintains they are just friends.
In addition to heavyweight boxer Klitschko, the actress, 21, has also dated her former Heroes costar Milo Ventimiglia
as well as Hills
alum Stephen Colletti.
Reporting by JULIE JORDAN and BLAINE ZUCKERMAN