Dominic Thiem conceded his game was "just not there" after he let a two-set lead slip in a shock first-round loss to Pablo Andujar at the French Open.
Thiem had looked in command against a player with no previous top-five wins to his name. However, he crumbled thereafter, further opening a bottom half of the draw that is there for the taking with Novak Djokovic, Rafael Nadal and Federer all in the top half.
It left the two-time finalist at a loss to describe a massive upset that was the defining story of a day that saw Alexander Zverev, the man Thiem beat in last year's US Open final, battle to a five-set win.
There were no such exertions for Stefanos Tsitsipas, who cruised to a straight-sets win over Jeremy Chardy after the 9pm (local time) curfew in Paris robbed his opponent of the backing of the home crowd at Roland Garros.
"JUST NOT GOOD ENOUGH"
Thiem denied any talk of him lacking motivation against Andujar, the Austrian instead pointing to a complete loss of form as the reason for his collapse.
Speaking in the media conference after his 4-6 5-7 6-3 6-4 6-4 loss in nearly four and a half hours, Thiem said: "The game was just not there today.
"All the shots are missing power, they're not accurate enough. [I am] moving not well enough. Everything in my game, there are some percents missing, I actually don't really know why because since I stepped back on court it's already two months and I was really practising well."
Andujar might not have a top-five win, but he beat Federer – currently at number eight in the rankings after an injury absence – recently in Geneva.
Still, Thiem felt it was his own failings that were pivotal.
"Shots were there in practice and it got better in Madrid and Rome, but Lyon and here, the shots and how I moved was not the real me or my version who is able to play for big titles," Thiem said. "It's just not good enough at the moment. It's a very tough situation."
ZVEREV MAINTAINS PERFECT FIVE-SET RECORD
Zverev appeared set to join world number four Thiem in falling at the first hurdle when he fell two sets down to German compatriot Oscar Otte, the qualifier making just his third main draw appearance at a slam and playing in his first tour-level match this year.
But Zverev racked up 50 winners as he fought back to claim a 3-6 3-6 6-2 6-2 6-0 victory, stretching his perfect record in five-setters at Roland Garros to seven matches.
It marked the second time Zverev has produced a turnaround from two sets down, having achieved that feat to reach the US Open final by beating Pablo Carreno Busta, who overcame Norbert Gombos in straight sets on Sunday.
TSITSIPAS SEES OFF CHARDY
In terms of laying down an early marker, it was Tsitsipas who perhaps produced the greatest statement of intent on day one, though the coronavirus restrictions meant there were no fans on court to see it.
Had there been spectators, they might have helped Chardy prevail in the key moments in a tight opening set that saw Tsitsipas save a set point and then win it on a tie-break.
From there, the fifth seed was always in command and surged to a 7-6 (8-6) 6-3 6-1 triumph.
HURKACZ HIT BY BOTIC BLITZ
Roberto Bautista Agut and Karen Khachanov were routine winners on day one while Cristian Garin prevailed in four sets against Juan Ignacio Londero.
Dan Evans, the 25th seed, went out as he lost in four sets to Miomir Kecmanovic and injury ended the hopes of 16th seed Grigor Dimitrov.
Dimitrov had three match points at 6-2 6-4 5-1 against American Marcos Giron but let them slip and promptly lost the next eight games before retiring with a back problem.
Also crashing out was Hubert Hurkacz, the 19th seed undone by Dutch qualifier Botic van de Zandschulp, who came from two sets down in a stunning display.
Van de Zandschulp won seven of his 14 break points and reeled off 55 winners in an incredible turnaround to seal a 6-7 (5-7) 6-7 (4-7) 6-2 6-2 6-4 win.