The German star was just four minutes into his first start for Chelsea, and for some reason decided to mark the occasion with a sickening late challenge on QPR's Cameroonian star.
Mbia managed to leap clear before his leg was broken, but somehow referee Lee Mason decided to be lenient - despite far more innocuous challenges this season having drawn dismissals.
Amazingly, QPR manager Harry Redknapp claimed that he believed Marin did not deserve to go, reasoning that there could not have been any malice in the challenge: "Marin is not a nasty person. I don’t think he’s that kind of player, so we’ll give him the benefit of the doubt."
Of course, it might just have been the famous 1-0 victory enjoyed by QPR over Chelsea that might have put Redknapp in too good a mood to start pointing fingers. Either way, Marin can count himself lucky not to have clocked up his first red card and his first start within five minutes of each other.
What do you think? Should Marin have been dismissed, or was Harry Redknapp correct to say that it was a challenge that wasn't as bad as it looked? Watch the video above (UK users only) and have your say below.