Tokito Oda (left) broke Alfie Hewett's serve five times in the Briton's 10 service gamesGreat Britain's Andy Lapthorne won a second French Open quad wheelchair doubles title but compatriot Alfie Hewett was denied a fourth Roland Garros singles crown by Tokito Oda.
Lapthorne and South Africa's Donald Ramphadi beat second seeds Robert Shaw and Heath Davidson 1-6 6-2 10-3.
But three-time men's wheelchair singles champion Hewett lost 6-1 6-4 to Japanese 17-year-old Oda.
The teenager also replaces Hewett as world number one with the victory.
Hewett returns to action later on Saturday alongside Gordon Reid as the Britons, champions in Paris for the past three years, seek a 17th Grand Slam title together.
The top-ranked duo, who are contesting a 15th consecutive Slam final, face Spain's Martin de la Puente and Argentina's Gustavo Fernandez on court 14.
It was on that same court that Lapthorne claimed a 14th doubles Slam crown alongside new partner Ramphadi as they came from a set down to beat Australia's Davidson and Canada's Shaw.
"This is the first time we've played together and we've ended up winning, so hopefully it's a sign of things to come," Lapthorne said.
'Many more finals between us ahead'
Oda and his coaching team were overwhelmed by the teenager's first major title, embracing each other in tears amid emotional scenes on the tournament's main show court, Court Philippe Chatrier.
The win means he becomes the youngest men's wheelchair singles world number one, claiming revenge for his defeat by Hewett in the Australian Open final earlier this year.
"You fully deserved that title today, that was simply amazing out there - and for a young lad, that's seriously impressive," a gracious Hewett told the champion in his post-match interview.
"I'm sure there are going to be many more battles and finals between us ahead.
"I want to say a massive 'thank you' to Roland Garros for giving myself and Tokito the opportunity to play in this incredible arena.
"It's my first time playing here and it is as good as it looks on the TV - I'm really happy to play here, not so happy with the result but we move on and there's Wimbledon next so I'm looking forward to that."
Oda twice broke serve in a dominant first set before repelling a second-set fightback from seven-time Grand Slam singles champion Hewett to see out the win.
