David Beckham will compete in the world's toughest triathlon with his friend Gordon Ramsay.

The pair have been training so hard for the gruelling Ironman event that pals have nicknamed them 'Rocky' and 'Apollo' from the iconic 1976 boxing flick 'Rocky', starring Sylvester Stallone.

The retired soccer superstar gave Gordon fitness tips when the 46-year-old TV chef was preparing earlier this month for the triathlon in Kona, Hawaii. And now he's recruited him as a sidekick for next year's event.

In just over 14 hours, Gordon conquered the 112 mile cycle ride, 2.4 mile swim and a 26.2 mile run.

A friend of David, 38, told the Daily Star newspaper: ''David became jealous of Gordon after giving him training advice.

''He misses competing since retiring from soccer so it didn't take long for Gordon to convince him to do it.

''They've been getting up at 4am to train on the beach. Friends are joking they're like the leads from Rocky with their dedication.''

The potty-mouthed chef has lost over 28 lbs after a year of following a strict diet and exercise regime in preparation for the triathlon.

The 'Kitchen Nightmares' star traded fatty foods for super-healthy alternatives, including vegan shakes, almond milk and lots of fresh vegetables, he also works out three to four days a week.