Murray and Nadal sail through as Wawrinka crashes out
Day one at Wimbledon produced a major surprise as world number three Stan Wawrinka lost to Russian debutant Daniil Medvedev.
Defending men's champion Andy Murray celebrated the news that he is about to become a father again by reaching the second round.
The top seed and world number one downed Kazakh lucky loser Alexander Bublik 6-1, 6-4, 6-2, showing little sign of the hip problem which plagued him in the build-up.
"I have felt OK the last few days and the adrenaline you feel by playing a match numbs any pain you may have," said the British star after seeing off world number 134 Bublik.
Murray next faces Dustin Brown, the man who knocked out Nadal two years ago.
Rafa cruises through round one
World number two and two-time champion Nadal secured his 850th career victory with a 6-1, 6-3, 6-2 demolition of Australia's John Millman.
Fresh from winning his 10th French Open title, Nadal goes on to face Donald Young for a place in the last 32.
"I haven't had many matches on grass for the last few years, but I had some positive feelings," said Nadal, who missed last year's tournament with a wrist injury.
Stan says goodbye to SW19
Swiss fifth seed and French Open runner-up Wawrinka was knocked out by Russia's Daniil Medvedev, 6-4, 3-6, 6-4, 6-1.
World number 49 Medvedev, making his Wimbledon debut, handed 33-year-old Wawrinka a sixth first round loss at the All England Club, although his efforts were hampered by a left knee injury which required an ice pack at the changeovers.
"I wasn't feeling the way I wanted to feel. But I played against a great player who was confident," said Wawrinka whose pain was eased slightly when girlfriend Donna Vekic won her opening match.
Medvedev, 21, kissed the Centre Court grass to celebrate his victory, his first at any Slam.
"A year ago I was ranked 250. If someone told me in one year I would win on Centre Court I would tell you you are joking," said the wirey Russian.
Nick Kyrgios, who beat Nadal at Wimbledon in 2014, will not get another opportunity to repeat that shock.
The combustible 20th seeded Australian was 6-3, 6-4 down to France's Pierre-Hugues Herbert when he called it quits after failing to shake off the hip injury which has plagued him in recent weeks.
Women's second seed Simona Halep, blasted off court in the French Open final by Jelena Ostapenko, downed New Zealand qualifier Marina Erakovic 6-4, 6-1.
Ostapenko, the 2014 Wimbledon junior champion, saw off Aliaksandra Sasnovich of Belarus 6-0, 1-6, 6-3.