'I'm very excited': Conor McGregor spends more time with ROYALTY as ex-UFC king hails 'AMAZING athletes' at Tour de France (VIDEO)

Former UFC champion Conor McGregor has accompanied Prince Albert II and Princess Charlene to launch the 2020 Tour de France in Nice, joining Monaco's royalty again after training with the princess for a marathon water biking test.

The retired fighter pictured himself heading to the start of the rescheduled race in style, sitting in a car as part of a royal procession heading to the 107th edition of cycling's most famous race.

McGregor had been on his bike earlier this week, spending time pedaling on the water alongside cycling coach and conditioner Colin Byrne and Julian Dalby, the co-founder of his McGregor Fast fitness plans.

Tour bosses invited McGregor to offer a message to the 19 teams competing in the 2,156-mile race ahead of the start on Saturday.

Speaking in a video published by the tour on Twitter, where it has more than three million followers, the masked McGregor announced: "It's an honor to be here witnessing these amazing athletes taking part in their sport.

"I'm very excited to be here and I wish all of the athletes good luck."

Almost three months after announcing his retirement from the Octagon for the third time, McGregor has maintained his fitness by stepping up his training for the marathon endurance race across the Mediterranean next month.

The water biking contest, in which McGregor and former Olympic swimmer for South Africa Charlene will cover 112 miles, starts in Corsica on September 12 and finishes at Monaco's Yacht Club the following day.

"Great work today with Her Highness," McGregor told his Instagram following of almost 37 million on Thursday, promoting the crossing to raise awareness of water safety and ocean hygiene.

"[We are] training between the elements of night and day to prepare for our voyage from Corsica to Monaco by sea bike.

"We are estimating upwards of 30 hours for completion. We are ready."

McGregor also congratulated his coach, John Kavanagh, on the arrival of his new baby earlier this week and posed with fiancee Dee Devlin, who he has been spending time with on a yacht.

The 32-year-old also marked the third anniversary of his encounter with Floyd Mayweather, picturing himself clinching his former foe in the most lucrative boxing match in history.

"Three years ago today I carried Floyd for his final boxing match," he reminisced.

"Wow, time flies when you’re stacking Cheddar. Happy retirement, champ."