Olympian RYAN LOCHTE off the deep end for BLAKE LIVELY!

 RYAN REYNOLDS better watch his back! Olympic swimming champ RYAN LOCHTE has the hots for his girl!

“She makes my toes curl!” the 28-year-old athlete told a reporter about his feelings for Reynolds’ live-in love, “Gossip Girl” star Blake Lively.

Friends say the Florida-based swimming stud has a serious crush on Blake and that’s NOT sitting well with the “Green Lantern” star!

“Ryan’s a very jealous guy and he’s not thrilled at the attention his girlfriend is getting from Lochte,” said a source. “His attitude is, ‘Back off, buddy, she’s mine!’”

Blake, 24, and Reynolds, 35, have been dating for almost a year and currently share a $2 million cottage home in Bedford Hills, N.Y. “They’re already acting like a married couple,” the source continued.

In fact, cops in Bedford Hills referred to Blake as Reynolds’ “wife” in a police report after the actor made a complaint about a suspicious vehicle parked in front of their home in early July.

Lochte is riding high after the London Olympic Games, dishing out a stunning upset to fellow racer and teammate Michael Phelps.

 The source said the Olympic star “isn’t going to actively pursue Blake in order to win her over. But if she and Ryan Reynolds break up, he wouldn’t mind helping her get over her broken heart!”