Andrey Rublev suffered a shock early exit at Wimbledon on Tuesday as numerous other seeds progressed through to the second round.
Rublev, a 17-time ATP Tour champion, reached the quarter-finals at this tournament last year but failed to make it past his opener this time after Argentine Francisco Comesana upset the sixth seed.
Comesana triumphed 6-4 5-7 6-2 7-6 (7-5) on No.2 Court, where play was disrupted by heavy downpour, as Rublev became the highest-ranked male player to fall so far at the All England Club.
Unlike Rublev, fourth seed Alexander Zverev coasted past Roberto Carballes Baenai in straight sets on No. 1 Court.
"I want to compete, I want to do well here at Wimbledon. It's the most historic tennis tournament that we have," Zverev said after reaching the second round for the seventh time in eight attempts at this tournament.
"I've struggled over the years here on these beautiful courts, unfortunately, but I feel different this year."
Hubert Hurcakz progressed through his first challenge, though the seventh seed conceded the first set before defeating Radu Albot 5-7 6-4 6-3 6-4, smashing 24 aces in the process.
Alex de Minaur headed into this year's edition as the ninth favourite and his opening performance befitted that status, overcoming fellow Australian James Duckworth 7-6 (7-1) 7-6 (7-3) 7-6 (7-4).
Stefanos Tsitsipas fought off Taro Daniel with a 7-6 (7-5) 6-4 7-5 in just under two-and-a-half hours as the 11th seed aims to go further than his personal-best fourth-round appearances in 2018 and five years later.
It was not so straightforward for British number one Jack Draper, who secured a hard-fought 3-6 6-3 6-3 4-6 6-3 victory over Elias Ymer under the lights on Centre Court.
Draper is in fine form, having won the Stuttgart Open in June and defeating Carlos Alcaraz at the Queen's Club Championship, and will next meet fellow British player Cameron Norrie.
World number 42 Norrie had little trouble in his first-round test, dispatching Facundo Diaz Acosta in straight sets on No.3 Court.
Data Debrief: Comesana on cloud nine as Zverev powers through
Comesana may have expected to compete with Rublev in his first-round encounter, but this was only his second appearance on grass courts of his career at any level, professional or junior.
The world number 122 managed to battle to a hard-fought triumph after a clinical showing, converting four of five break points he earned.
Zverev had no such difficulty in progressing to the second round, powering 18 aces at an event he has never reached the quarter-finals in.
The German is now 12-2 for the year in major action, having reached the semi-finals at the Australian Open and the showpiece at the French Open before defeat to Alcaraz.