Draper is a fine talent with ambitions of reaching the world's top 10, but this defeat was another example of the work he still has to do.

The left-hander recently brought South African former world number nine Wayne Ferreira into his coaching team to help achieve his goal, saying before he faced De Jong that his game - particularly his serve - is in transition.

Only landing 50% of his first serves, and winning just 51% of second-serve points, were indicative of that.

Double faults also came at costly moments, none more so than the one at 30-40 in the seventh game of the decider which helped De Jong secure victory.

"My serve has been a problem this year. I'm trying to change it to make it better," Draper said.

"The confidence isn't there at the moment on my serve, and it's a problem I'm going to have to work on. It's really letting me down."

While Draper struggled, 23-year-old De Jong showed assurance after his three qualifying victories to reach the main draw.

De Jong took a tight first set by breaking Draper in the 12th game and won the final four games of the set.

None of Draper's seven previous defeats in a Grand Slam main draw had come in straight sets.

A fine forehand winner down the line arrived at a timely juncture in the tie-break and Draper improved further to move a break up in the fourth. After an 80-minute rain delay, he took the match into a decider.

Only once had the Briton played a five-set match - when he came through to beat Marcos Giron in brutal conditions at this year's Australian Open.

That felt like a landmark moment in Draper's career, showing he had built up the physical and mental resilience to overcome adversity.

However, Draper was unable to win another Grand Slam decider as De Jong set up a second-round meeting with Spanish third seed Carlos Alcaraz.

"[Last year] I couldn't manage near to three sets, and now this is probably I think the longest match I've played," Draper said.

"I didn't cramp. I didn't break down. The issue today wasn't physicality. It was my tennis. So I think that's a real positive."