Jennifer Lopez's relationship with backing dancer Casper Smart continues to heat up during their vacation in Miami.

The 42-year-old singer and her toyboy beau, 24, were seen walking hand in hand yesterday while they went shopping along South Beach.

They stopped in a store to check out designer sunglasses but they did not appear to make a purchase.

The Jenny From The Block star was dressed down in tan trousers and a matching tank top while Casper wore jeans, a black T-shirt and a beanie hat.

Jennifer and Casper have only been dating for a short while but are already inseparable having travelled around the country together over the past few weeks.

"Just saw Jennifer Lopez and new boy toy holding hands walking down Lincoln Road," a passerby tweeted about the loved up pair.

The couple saw in the new year in the Sunshine State and have been pictured on a luxury yacht and going for nights out at Soho Beach House.

Eyewitness saw Casper stroking Jennifer's face and the pair danced suggestively with each other into the early hours.

Casper wrote on his Twitter page on New Year's Day that he had just "drove some 120mph go carts" but his speeding in the past has got him into trouble which he will have to face this week.

He is due in court in Van Nuys, California on Thursday stemming from his arrest in April 2010 for illegal drag racing.