Katy Perry is reportedly dating her “most embarrassing crush” – US singer-songwriter Josh Groban. Talk about an unlikely couple.

The pop babe has been single since splitting with long-term beau Travis McCoy during a make-or-break festive trip to Mexico.

Heartbroken Katy subsequently took a vow of celibacy and swore off men for the duration of 2009, but rumors are mounting stateside she’s found love with Josh.

A source told [he who blogs from under the stairs]:

“They’ve been trying to keep it very low profile.”

Katy recently confessed Josh was her number one crush – and her most shameful one.

She said:

“Who’s my most embarrassing crush? I suppose it would have to be Josh Groban.

He is actually really cute!”

And probably a little offended…