Thomas and rising star Bernal are sharing leadership duties after four-times winner Chris Froome was ruled out by serious injuries sustained while warming up for a stage at the Critérium du Dauphiné last month.

The 33-year-old Thomas is hoping he and his 22-year-old Colombian team mate, who won March’s Paris-Nice and June’s Tour de Suisse, can flourish following the Grand Départ in Belgian capital Brussels.

"We're not rivals," Thomas told BBC Sport.

"He’s a really humble, family-orientated guy and I trust him.

"That's the key – communication and trust, which Froomey and I had.

"At the end of the day, we'll know deep down who's in the better position at the time.

“As long as we trust each other and nobody does anything out of the blue, we should be fine."

Thomas is one of two former champions returning to contest the 21-stage, 2,150-mile race, the other being Bahrain-Merida’s Vincenzo Nibali of Italy, who triumphed in 2014.

With Froome and Team Sunweb’s Tom Dumoulin of the Netherlands absent due to injury, this year's Tour is viewed by many as an open contest.

Among the riders who could be in the running for general classification victory are Astana’s Jakob Fuglsang of Denmark, Mitchelton-Scott’s Adam Yates of Britain and Trek-Segafredo’s Richie Porte of Australia.

The opening stage will begin and end in Brussels, visiting Charleroi along the way as part of a 119-mile route.

The Tour is due to run until July 28 when the riders reach the streets of Paris.