Top seed Novak Djokovic overcame a dogged challenge from 81st-ranked Korean Kwon Soon-woo and his own grasscourt rustiness to reach the Wimbledon second round.
The defending champion registered a 6-4 3-6 6-3 6-4 victory on Monday.
Djokovic, who is bidding for his fourth Wimbledon title in a row and his seventh overall, looked out-of-sorts at times against Kwon, who brought a lively mixture of tennis, from booming forehands to delicate drop-shots, onto Centre Court.
Djokovic had not played a grasscourt warm-up tournament and he admitted that did not help his game against a tough opponent, 11 years his junior.
Elsewhere, Norwegian third seed Casper Ruud registered his maiden Wimbledon victory in his third main-draw appearance when he saw off experienced Spaniard Albert Ramos-Vinolas 7-6(1) 7-6(9) 6-2 in the first round.
French Open runner-up Ruud failed to get past the opening hurdle in 2019 and 2021 and arrived at this year's grasscourt Grand Slam following a first-round loss at Queen's to world number 180 Ryan Peniston.
In the women's competition, Emma Raducanu marked her Centre Court debut with a 6-4 6-4 win over 10th seed Alison Van Uytvanck of Belgium.
Britain's US Open champion was playing her first match since retiring from a match due to a rib injury three weeks ago.
Third seed Ons Jabeur powered past Mirjam Bjorklund 6-1 6-3.
The Tunisian, a quarter-finalist last year, showed no signs of being hampered by the knee injury that forced her out of the Eastbourne tune-up event.
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