*Rihanna is on best friend duty for her homie Katy Perry in the wake of her divorce from Russell Brand.

Perry, who spent the holidays in Hawaii with friends – has shared a number of phone calls with RiRi as she deals with the end of her 14-months marriage, and the “We Found Love” singer has been a “great support” in helping her cope, a source told The Sun.

“Katy is hardly speaking to anyone right now, but she called Rihanna as soon as she heard Russell was filing for divorce,” said the source. “Katy was embarrassed about calling her parents as they’d been so against Russell in the first place, but Rihanna was a great support for her and she really helped to calm her down.”

Rihanna is now said to be planning a Mexico getaway with Katy to help her get over Russell.

An insider told the Daily Mirror newspaper: “”Rihanna has been there for Katy, texting her from Miami where she’s on holiday. Now they are planning a girlie getaway so Katy can clear her head.”

While Russell – who is rumored to be moving back to the UK following the split from Katy – is entitled to half of the singer’s estimated $70 million fortune under Californian law, the pair have vowed to part as “friends” and want the split to remain amicable.