Alexander Zverev and Stefanos Tsitsipas - the supposed next generation of men's tennis - have become shock casualties in the first round at Wimbledon.
Novak Djokovic's potential path to the final looks even clearer, after the young guns, both in the defending champion's half of the draw, fired blanks on the opening day in London.
Sixth seed Zverev went down in four sets to qualifier Jiri Vesely, the world number 124.
The 22-year-old slipped at a crucial moment to give away two match points and then netted the first, as Czech ace Vesely celebrated a surprise 4-6 6-3 6-2 7-5 triumph.
Zverev, who has endured a poor year so far, admitted his confidence has taken a battering and alluded to issues off the court.
"When I get to the important moments - and I had five or six break points in the fourth set alone - I can't take any of those," he said.
"I'm down one break point myself and he takes it immediately, where I miss an easy volley. I didn't lose this match on tennis - it's just my confidence is below zero right now.
"The last two days, I would say [were] very rough for me personally. I'm not going to get into details, but I'm just saying.
"I have to fix that to play well on the court."
About 20 minutes later, after saving two match points in the fourth set, Tsitsipas
succumbed to the third, as he was turfed out 6-4 3-6 6-4 6-7 (8-10) 6-3 by Italian Thomas Fabbiano.
Zverev and Tsitsipas are supposedly at the head of the pack attempting to chase down Djokovic, Roger Federer and Rafael Nadal.
On this evidence, the big three are still a long way in the lead.
Djokovic was the first of the gilded trio to flex his muscles at this year's championships, the Serbian opening proceedings on centrecourt against Philipp Kohlschreiber.
The world number one double-faulted the opening point on his way to dropping serve in the first game.
But order was soon restored, Djokovic broke straight back and then wore his German opponent down in a 6-3 7-5 6-3 win.
Last year's runner-up, Kevin Anderson, eased into round two, with a 6-3 6-4 6-2 win over Pierre-Hugues Herbert.
Three-time Grand Slam winner Stan Wawrinka made short work of Belgian Ruben Bemelmans, the Swiss roaring to a 6-3 6-2 6-2 victory in less than an hour-and-a-half.
Felix Auger-Aliassime dropped the first set against fellow Canadian Vasek Pospisil, but recovered to win 5-7 6-2 6-4 6-3 on their country's national day.
Ivo Karlovic is still going strong at 40, beating Italian Andrea Arnaboldi 6-4 6-4 7-6 (7-4).
The Croatian - the oldest man to play in the singles event since Ken Rosewall in 1975 - will face Fabbiano in round two.
AAP
