Serena Williams enjoyed a successful Wimbledon comeback with a gutsy win over Arantxa Rus.
The seven-time champion did not play at SW19 in 2017 as she was pregnant with her daughter, but announced her return with a 7-5 6-3 win in breezy conditions on Court One.
Williams, who pulled out of the French Open last month with an arm injury, was a break down in the second set but fought back to win in straight sets.
She was made to work hard for it, eventually sealing victory on a sixth match point.
US Open champion Sloane Stephens crashed out in the first round of Wimbledon after a straight sets defeat to Donna Vekic.
Stephens, who was runner-up at the French Open last month, was downed 6-1 6-3 by the unseeded Croatian.
It was a tough draw for the fourth seed as Vekic is a threat on grass but Stephens put in an erratic display in her first match on the surface this season.
US Open champion Sloane Stephens crashed out in the first round of Wimbledon after a straight-sets defeat to Donna Vekic.
Stephens, who was also the runner-up at the French Open last month, was downed 6-1 6-3 by the unseeded Croatian.
It was a tough draw for the fourth seed as Vekic is a threat on the grass but Stephens put in an erratic display.
The American had not played since that loss to Simona Halep in Paris and her ring-rust showed as Vekic dominated from the off.
She raced to the first set in just 26 minutes with two breaks of serve but found herself on the back foot when Stephens broke to lead 2-0 early in the second.
Stephens could not capitalise, though, as Vekic won six of the next seven games to complete the biggest Wimbledon scalp of her career after previous first-round exits to Venus Williams and Johanna Konta in the last two years.
"I am very happy to win today, it was a tough match," Vekic said. "I am really happy.
"I tried to go out there and be aggressive, I was struggling with my serve, it was windy, so I am happy to get through.
"I played all the tournaments on grass, I really enjoy playing on it and it helped me."
Elsewhere, fifth seed seed Elina Svitolina was a late-night casualty as she went down to Tatjana Maria.
The Ukrainian would have been hoping to make a real challenge for her maiden grand slam, but lost 7-6 (7/3) 4-6 6-1.
Caroline Wozniacki safely navigated her way past Varvara Lepchenko, winning 6-0 6-3, just 48 hours after claiming the Nature Valley International in Eastbourne.
Five-time champion Venus Williams overcame a scare to beat Swede Johanna Larsson.
Williams came back from a set down to win 6-7 (3/7) 6-2 6-1.
Karolina Pliskova also had a battle on her hands to get past British hopeful Harriet Dart in three sets.
Coco Vandeweghe lost her battle with Katerina Siniakova, who won 6-7 (3/7) 6-3 8-6.
The American, seeded 16th, was hampered by an injury sustained in the first set but fought on bravely.
She eventually went down in a three-set epic that lasted three hours and four minutes.
Agnieszka Radwanska, a finalist in 2012, survived by the skin of her teeth to beat Elena-Gabriela Ruse.
The Pole saved six match points to win 6-3 4-6 7-5 and scrape through to the second round.
Magdalena Rybarikova was the first seed to lose as she was beaten 7-5 6-3 by Sorana Cirstea while 22nd seed Anastasija Sevastova was ousted 6-1 2-6 6-4 by Camila Giorgi.
Former world number one Victoria Azarenka came through in straight sets against Ekaterina Alexandrova while 2015 quarter-finalist Madison Keys eased past Ajla Tomljanovic 6-4 6-2 in 63 minutes.
There were also wins for Lucie Safarova, Kristina Mladenovic and Barbora Strycova.
