Kyle Edmund, Heather Watson progress at Roland Garros

World number 121 Edmund is 15 years Robert's junior and his youthful fitness - and booming forehand, which looks an impressive and dangerous weapon - proved decisive.

Considering their rankings this was a high-quality encounter and light was fading when Edmund finally secured his 2-6, 6-4, 6-3, 5-7, 6-2 victory in just under three hours.

"It feels so good, at 2-2 I knew I had to give it my all - this is what all the training is for, moments like this," said Edmund, who faces Australia's Nick Kyrgios in the second round.

"I started cramping and my arms were in agony and I was wondering how I was going to play, I'm just so pleased to get through.

"It's daunting having the crowd against you, they are passionate about their players but you want to experience matches like this, coming to a guy's backyard and beating him."

Meanwhile, Heather Watson admitted there was room to improve as she progressed to the second round with a straight sets win.

The British women's number one made a stuttering start against home hope Mathilde Johansson when she lost her opening service game.

It was to prove a pattern for the match - with both players losing their serves a total of 11 times before Watson advanced 6-4, 7-5.

Johansson was up 4-2 in the second set and even had the chance to serve to level the match but her 42 unforced errors were ultimately decisive.

However, Watson will need to improve for her second round match with Australian Open semi-finalist Sloane Stephens, who beat 15th seed Venus Williams 7-6, 6-1.

But she has beaten the American in their four previous encounters, including twice on clay and most recently a 6-3, 6-1 victory in Hobart in January.

Five British players were looking to make second round in Paris for the first time in 35 years but Andy Murray, Edmund and Watson are left to fly the flag after their two compatriots both slipped to defeats.

Aljaz Bedene's first Grand Slam as a British player ended with a 6-3, 6-4, 6-7, 6-3 defeat to Austria's Dominic Thiem.

Slovenian born Bedene has spent seven years training at Welwyn Garden City and the world number 75 was granted British citizenship in March and could appear for Great Britain in their Davis Cup quarter-final against France in July.

"I felt pretty confident out there but my slow start was probably the difference," he admitted.

Qualifier Johanna Konta will look back with regret on a first set tie-break after a battling encounter against Czech Republic player Denisa Allertova.

Konta, in her debut in Paris, was edged out 19-17 in an epic first set tie-break and while she bounced back to force a deciding set, she went down 7-6, 6-4, 6-2.