Nicole Scherzinger is rumoured to be dating tennis ace Grigor Dimitrov. However, the 37-year-old former Pussycat Dolls singer's friends are worried that she will get close to the 24-year-old player too soon and break her heart.

Scherzinger split with Formula One ace Lewis Hamilton in February this year. The two started dating in 2007 and had been in an on-again, off-again relationship.

"Nicole really likes Grigor and loves spending time with him, but her friends are wondering whether she still has feelings for Lewis and have warned her to take things slowly," a source told Closer magazine. "Nicole and Lewis were together for such a long time and they're still in touch so her friends don't want her to get hurt."

It was previously reported that the former X Factor judge was tired of Hamilton's refusal to commit. However, the 30-year-old, who was rumoured to be dating Rihanna, apparently has not moved on yet.

"He's already told Nicole it will kill him to see her with someone else, let alone a younger sportsman," the insider added. "Nicole doesn't want to hurt his feelings but she can't put her life on hold. He won't settle down and, without the promise or marriage and babies, she's not going back."

During an interview with the Daily Telegraph, the Baby Love singer admitted that her busy career has taken a toll on her relationships with loved ones. She said: "I try not to regret things, because I feel like as long as you put positive energy towards something — and you put your whole self, your true self, towards it — it'll lead you to the next place you're supposed to be."

"I look at this as a great blessing for me to be able to take on this role... but I have made sacrifices," she added. "This is very time consuming. I've left LA, left all my friends and my family. It's sacrificing your time in relationships, with loved ones, and my work..."

In July, Dimitrov parted ways with five-times grand slam champion Maria Sharapova after two years of dating. He had also dated Serena Williams.