Davidovich Fokina has no regrets over failed underarm serve at Wimbledon
The Spaniard opted for the unorthodox tactic at 8/8 in the fifth set tiebreaker against sixth seed Holger Rune.
But the Dane spotted the move, sprinted forward and unleashed a forehand winner to go to match point.
A disconsolate Davidovich Fokina then buried a service return in the net, allowing Rune to celebrate a 6-3, 4-6, 3-6, 6-4, 7-6 (10/8) victory.
Davidovich Fokina, the 31st seed, had already squandered two match points in the 10th game of the decider.
Asked if he would make the same decision on serving underarm again, the 24-year-old said: "Why not? It was just another serve.
"I don't regret anything. I'm happy for this match that I did because I was struggling on grass and how I played today I convinced myself that I have a lot of things in myself."
Rune fired 19 aces in his haul of 61 winners during the four-hour third-round encounter.
As well as saving match points, he also recovered from 6/2 and 8/5 down in the fifth-set breaker.
Rune described Davidovich Fokina's rush of blood as "crazy".
"That was very unexpected but in a way, it was nice because he was serving really well during the match," he said.
"It's pressure because imagine I missed that one. That would feel awful."
Rune admitted, however, that he would never have taken such a risk at a crucial point of the match.
"I wouldn't do it, but every player has a different style. If he made it, it would have been the right shot.
"I would trust my serve and go big like I did in the match points I saved."
For Davidovich Fokina, it was a second successive nightmare exit from the All England Club.
Twelve months ago, he was penalised for ball abuse at 7/9 down in the fifth-set breaker against Jiri Vesely and lost the match.
He received a point penalty, which gave Vesely victory.
The 20-year-old Rune will face either Frances Tiafoe or Grigor Dimitrov for a place in the quarter-finals.
That match was halted because of rain on Saturday with Dimitrov having taken a two sets lead.