Britney Spears's Man Mystery Deepens

07/09/2007 at 04:00 PM EDT

Men seem to come and go in Britney Spears's life – quick: Who remembers the Manny? Or Isaac Cohen? – but buzz is building around the identity of the square-jawed man with tousled brown hair who's been out with her in recent days.

This weekend marked the latest public sighting of Spears with the man, who has been hiding behind dark shades. They turned up at Bel Air Presbyterian Church on Sunday, with Spears carrying son Jayden, who will turn 1 in September, and the man toting a crying Sean Preston, who's nearly 2.

Ruggedly handsome and good with kids – but who is he? Bodyguard? Boyfriend? A little of both? The Internet has been abuzz with speculation, but so far no positive IDs. Spears's reps also aren't saying and her Web site is absent any mention of him. He just emerged, often seen behind driving Spears around in her black Mercedes.

The church visit followed a very public night on the town last week, with Spears and the man going to LA's Pantages Theater see the musical Wicked – or at least the first part of it. Spears and the man ducked out about an hour into the show, though no offense was taken.

"She came in late, and stayed for about an hour and left," says Wicked rep Tim Choy. "She loves the show. She's seen it several times."

• Reporting by LYCIA NAFF