Jackson (Jesse Williams) is currently dating Mark's former love interest Lexie (Chyler Leigh).
Mark gave the duo his blessing last season but Dane has now admitted that he might struggle when he begins teaching Jackson.
"We're going to find out if Sloan is a good teacher or not," he told TV Guide. "He sees that Lexie really likes Jackson and that Jackson is a good guy, so it's more a situation that if you break her heart, I'll break your face."
Grey's Anatomy's creator Shonda Rhimes recently suggested that the relationships between Mark, Lexie and Jackson will continue to be a "viable triangle".
Grey's Anatomy will return with a two-hour season premiere on September 22 on ABC.
> 'Grey's Anatomy' to feature 'all boys' episode
> Read more Grey's Anatomy coverage
Watch a trailer for the new season of Grey's Anatomy below: