Nicole Scherzinger is dating tennis star Grigor Dimitrov.

A source told The Sun newspaper: "Nicole is dating Grigor. They're completely besotted with each other.

"But they've been careful not to be pictured together because they don't want the pressure of the relationship being in the public eye.

"Lewis knows and is very unhappy. It's made him realise he isn't over her.

"He's been desperately trying to talk to Nicole over the last few weeks."

However, it's not the first time 24-year-old Grigor has been caught up in a love triangle.

Sharapova, 28, openly battled with his tennis star ex-girlfriend Serena Williams, 34, for his affections before they officially began dating.

And he could now be facing a public feud with Formula 1 star Lewis, 30, who is said to have attended a private gig at a nightclub in London on the same night as Nicole, 37, earlier this month in a bid to win her back.

Nicole - who split from on/off boyfriend Lewis for good in February - was pictured kissing Swiss footballer Pajtim Kasami in June before being linked to 'Thinking Out Loud' hitmaker Ed Sheeran.