Jack Draper suffered semi-final heartache at the Next Gen ATP Finals after losing to the USA's Brandon Nakashima in four sets in Milan.
The British third seed had briefly recovered from a slow start, but Nakashima still got the job done 4-3[6] 1-4 4-2 4-3[5] in one hour and 38 minutes.
Unsurprisingly aggressive from the off, Nakashima brought up a break point in Draper's opening service game, which he failed to take, and the first set would go all the way to a tiebreaker.
Nakashima had managed to win at least two points on all of Draper's service games in the first set and sought to assert his dominance in the tiebreaker, but it was the Brit who would briefly go 2-0 up.
Aces soon followed for both men before Nakashima won the 14th point on Draper's serve to take the first set, but his galvanized opponent came out a different beast in the second set.
A love hold preceded Draper's first break of the game as he racked up the winners count, but he went 30-0 down in the third game before restoring parity with two aces.
Nakashima held to love in game four to stay in the second set for a little bit longer, and despite a double fault from Draper in the fifth game, the 20-year-old comfortably served it out to level the match.
Draper hit as many as 12 winners in the second set - doubling his tally from the opening round - and strong serves were the theme between the two youngsters after the halfway point.
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Seven aces were hit in the opening four games of the third set - four for Draper and three for Nakashima - but the front-footed American brought up a deciding point on Draper's serve in the sixth game.
Draper then sent a forehand long after a lengthy rally to cede the third set, and Nakashima - who won 92% of his first serve points - did not let his guard down in the third, also switching his game up with the classic serve and volley technique.
The 21-year-old continued to return expertly and piled the pressure on Draper, moving into a 30-0 lead in the fourth game of the fourth set before his counterpart sent an ace down the T to hold for 2-2.
However, Nakashima began to stutter in the fifth game - particularly on his first serves - handing Draper a break point at 40-40, which the Brit painfully wasted after sending a forehand just wide.
Serving to stay in the match, Draper let a 30-0 lead slip and sent a backhand into the net to bring up a match point for Nakashima, but he picked the perfect time to hit a magnificent ace and keep the fight going to a tiebreaker.
Despite finding himself 5-2 down in the tiebreaker, a mishit drop shot from Draper and stunning down-the-line forehand saw Nakashima win four points on the bounce and bring up another match point, as Draper sent one more backhand wide to bow out.
Nakashima will now battle for the title against the Czech Republic's Jiri Lehecka, who beat Switzerland's Dominic Stricker 4-1 4-3[4] 2-4 4-1 in their semi-final.