Alex de Minaur has been edged out by top-seeded Frenchman Jeremy Chardy in the Surbiton Trophy final.
The 19-year-old from Sydney, who was seeking to become the first teenager to win a Challenger Tour event on grass since Nick Kyrgios' success at Nottingham in 2014, lost 6-4 4-6 6-2.
De Minaur more than matched the wily 31-year-old - a former Australian Open quarter-finalist - for two sets on a roasting hot day in southwest London.
But after finally breaking the world No.86's big serve to claim the second set he was immediately broken back in the opening game of the third and Chardy closed out the win.
Despite the defeat, de Minaur's performances this week have earned him a spot in the world's top 100 – which gives him automatic entry for grand slam events.
He will rise to No.96 when the new rankings are released on Monday - one of only three teenagers in the top 100 - but it comes too late to guarantee him a place at Wimbledon.
De Minaur was granted a wildcard for the French Open and unless he is offered the same by Wimbledon he will need to go through qualifying to book his spot at the All England Club or hope for two players to withdraw.
"It's always bittersweet when you play a great tournament and not get it done in the end," de Minaur told AAP.
"It's happened a couple of times now, I just have to get out there and work harder. But I am very happy with my run this week but Jeremy was too good today."
De Minaur said cracking the top 100 was a goal for him at the start of the year and fully intends to stay there and move towards the top 50.
"It's a huge milestone and I couldn't be prouder," he said.
"Now its about pushing harder and getting to as high as I can.
"I'll know before qualifiers if I am in for Wimbledon, but if not then I will have to get there that way."
In addition to his coach Adolfo Gutierrez, de Minaur has also worked with Davis Cup captain Lleyton Hewitt this week and said it has been a huge boost having the former world No.1 in his corner.
"It's always great to have him by my side and he's been a great help to me as a player, I learn things everything day from him," he said.
"He's helped me believe in myself and at the same time reminding me of how to stay in the moment and try and weather the storm at times and give it all on every single point.
"That is what I want to be known for."