Sexual tension is running high on the Canadian set of Twilight Eclipse, where both onscreen vamp Robert Pattinson (Edward) and series werewolf Taylor Lautner (Jacob) have allegedly fallen hard for wispy co-star Kristen Stewart.

At this rate, we’re surprised these kids can keep their clothes on long enough to get any work done….

“Rob is really nervous that Kristen will fall for Taylor’s charms,” a set spy squeals in the August 24 issue of Star Magazine.

The insider claims Lautner, who is almost 18, “definitely has a crush on Kristen,” and is heartbroken that the 20-year-old actress “treats him like a little brother.”