OK! Exclusive: Is Jason Lewis Jen's Mystery Man?

Two days before New Year's Eve, OK! was the that A-list actress Jennifer Aniston had jetted off to Los Cabos, Mexico, with pals Courteney Cox and David Arquette — and a goateed mystery man. Now, sources are revealing to OK! that this man is likely hunky model-turned-actor Jason Lewis.

It's been rumored for weeks that the former Mrs. Brad Pitt, 38, and the 36-year-old Sex and the City stud have been dating. And if Jason is indeed the tall, fedora-wearing passenger who escorted Jen onto a private, Mexico-bound jet in Burbank, Calif., on Dec. 28, then they've obviously taken the relationship to a whole new level.

Jen's most recent relationship was with British model Paul Sculfor. Jason had previously dated actress Rosario Dawson for two years.

Stay tuned to OK! as details develop!