Jennifer Lopez burst into tears during her birthday bash on Saturday – and not because it suddenly dawned on her that she'd hit the big 4-0 a day previously.

The actress-turned-singer started blubbing when she realised husband Marc Anthony had arranged a surprise party.

The Latino singer had whisked the Hollywood star to New York's Edison Ballroom in a grey Bentley where she was met by a bunch of screaming fans and a marquee with her nickname 'Lola' spelled out in gold lettering.

It was at this point that the penny dropped for J-Lo and she was overcome with emotion.

Anthony called the event An Evening for Lola in honour of his wife.

The star was greeted by pals including Liza Minnelli, Ricky Martin and producer LA Reid, as well as friends and family members who had flown in to help her celebrate.