Serena & Caroline -- Kick Manhunt Into Overdrive ... With Hot Bikini Selfies

Serena Williams is pretty open about wanting to find a man ASAP ... and now she's going on the offensive -- posting a pretty hot body selfie to show off the goods.

The tennis star hit the pool at a fancy resort in the Bahamas with her BFF Caroline Wozniaki ... when they broke out the camera phones and starting firing away. The results were good.

As we previously reported, Williams just said last week that she "desperately" wants to settle down and have children -- but noted that she's currently single ... "not by choice."

Wozniaki was engaged to golf star Rory McIlroy ... but he broke things off earlier this year while they were sending out their wedding invitations.

Talk about post-breakup hotness ...