The Nightcrawler star made his Broadway debut playing opposite Wilson in Constellations, which won rave reviews when the show opened in January (15) - and it appears the pair's onstage chemistry has spilled over into the actors' real lives.

Gyllenhaal was first romantically linked to his British colleague in December (14), and now it appears they have gone public with the relationship after sharing a "passionate" kiss after attending a fitness class together at Barry's Bootcamp gym in Manhattan on Saturday (09May15).

Sources tell the New York Post the actor left the venue alone, while Wilson later emerged with a group of friends.

The news comes weeks after Gyllenhaal claimed he was single in an interview with U.S. talk show host Ellen DeGeneres last month (Apr15).

During the chat, he revealed his mother, screenwriter Naomi Foner, has been trying to set him up on dates, saying, "My mother believes, she thinks arranged marriages might be able to work. You know what I mean? Like, in a good way. She thinks that if she picked for me that I'd do a lot better."

Gyllenhaal previously dated Taylor Swift, Reese Witherspoon and Sports Illustrated models Alyssa Miller and Emily DiDonato.