Stefanos Tsitsipas beat Dominic Thiem in a five-set first-round Wimbledon epic to set up a Centre Court meeting with Britain's Andy Murray.
The 24-year-old Greek won 3-6 7-6 (7-1) 6-2 6-7 (5-7) 7-6 (10-8) in a match that lasted three hours 56 minutes.
Novak Djokovic continued his pursuit of an eighth title by beating Australia's Jordan Thompson 6-3 7-6 (7-4) 7-5.
Elsewhere, there were wins for American seeds Taylor Fritz, Frances Tiafoe and Tommy Paul, but Sebastian Korda lost.
Murray beat fellow Briton Ryan Peniston on Centre Court on Tuesday, one of only eight matches to be completed on day two.
The 36-year-old home favourite would have therefore been pleased to see fifth seed Tsitsipas involved in a gruelling encounter with 2020 US Open champion Thiem, played out over two days on a packed Court Two.
Austrian Thiem took the opening set on Tuesday and led 6-3 3-4 before rain meant the match had to be suspended and finish on Wednesday.
Tsitsipas took the second set on a tie-break, then the third to go ahead, but he lost the fourth set, also on a tie-break.
The deciding set went to a match tie-break and Tsitsipas, watched by girlfriend Paula Badosa in the latter stages after her own win, clinched victory at the second attempt after missing an earlier match point.
"I'm not expecting anyone to support me," Tsitsipas joked before Thursday's match against two-time champion Murray.
"Andy is someone who has done so much for the sport and and I have a lot of respect for the opponent I'm facing."
Djokovic overcomes battling Australian Thompson
Djokovic, aiming to match Roger Federer's men's record of eight Wimbledon titles, advanced to round three with a straight-set win over world number 70 Thompson.
Thompson, 29, sent down 21 aces throughout the match, but he consistently struggled to make an impact against the Djokovic serve and failed to create a break-point opportunity.
A break for Djokovic in the seventh game proved crucial in the opening set, but the second was more closely fought as Thompson saved break points in the fifth and seventh games to force a tie-break, which Djokovic won, aided by two aces.
The third set looked to be following the same pattern, but Djokovic broke Thompson's serve in what proved to be the final game of the match for the win.
Djokovic, who has won this tournament in each of the past four times it has been held, will next face either 29th seed Tomas Martin Etcheverry of Argentina or 38-year-old Swiss player Stan Wawrinka, a three-time Grand Slam winner and old foe.
"Centre Court, Wimbledon has been the most special court without doubt throughout our tennis history," said 36-year-old Djokovic, who has not lost on the court since going down to Murray in the 2013 final.
"It's a huge privilege at this age and stage of my career, trying to push the young ones. We have a romantic and special relationship with the court."
A mixed day for American seeds
There has not been an American men's singles winner at Wimbledon since Pete Sampras landed the seventh of his titles in 2000.
Indeed, no man from the United States has won a Grand Slam men's singles title since Andy Roddick's success at the 2003 US Open.
However, the US have three of the top 15 in the ATP rankings - and all were in action on Wednesday.
Fritz's match with Germany's Yannick Hanfmann began on Monday but could not be completed because of bad light, with rain on Tuesday also frustrating the pair.
Seeded ninth, Fritz won four games in succession upon the resumption on Wednesday to triumph 6-4 2-6 4-6 7-5 6-3.
Tenth seed Tiafoe, a grass-court event winner at the Stuttgart Open last month, beat China's Wu Yibing 7-6 (7-4) 6-3 6-4.
Paul, who is ranked 15th but seeded 16th at Wimbledon, defeated Shintaro Mochizuki 7-5 6-3 6-1.
Another American, Ben Shelton, seeded 32nd, overcame Japan's Taro Daniel in five sets, winning 6-4 6-3 3-6 4-6 6-3, but 22-year-old compatriot Sebastian Korda, 25th in the world, suffered a shock 7-6 (9-7) 4-6 6-2 6-3 loss to Jiri Vesely of the Czech Republic.
Canada's Milos Raonic, beaten by Murray in the 2016 final, secured his first win at Wimbledon since 2019 after suffering a host of injuries, notably an Achilles problem.
The 32-year-old served 28 aces as he beat Austria's Denis Novak 6-7 (5-7) 6-4 7-6 (7-5) 6-1 to move into the second round.
Italy's Jannik Sinner, the eighth seed, is into the third round after a 7-5 6-1 6-2 win over Argentina's Diego Schwartzman.
In other first-round matches, there were wins for Argentina's 18th seed Francisco Cerundolo and Canada's Denis Shapovalov, seeded 26th, but Spain's Roberto Bautista Agut and Tallon Griekspoor of the Netherlands, the 20th and 26th seeds respectively, lost.