Former Wimbledon champion Maria Sharapova's injury problems continued as she retired from her first-round match against Pauline Parmentier.
The 2004 winner trailed 4-6 7-6 (7-4) 5-0 when she pulled out because of a problem with her forearm.
Former world number one Sharapova, 32, is now ranked 80th and only returned from a shoulder injury last month.
"I got myself into a good enough place to be part of this event and this is not what I wanted," said the Russian.
"I've had a history of a tendon problem in my left forearm and it flared up in the first set."
It is the second successive year the five-time Grand Slam champion has exited Wimbledon in the first round, having missed the 2016 and 2017 tournaments while serving a suspension for doping.
France's Parmentier, 33, will play Spanish 30th seed Carla Suarez Navarro in round two.
Elsewhere, ninth seed Sloane Stephens beat Swiss Timea Bacsinszky 6-2 6-4 to set up a second-round meeting with China's Yafan Wang.
Two-time champion Petra Kvitova cruised through with a 6-4 6-2 victory against Tunisia's Ons Jabeur. The Czech sixth seed, winner in 2011 and 2014, will face France's Kristina Mladenovic in the next round.
However, 2017 champion Garbine Muguruza, seeded 26th, was beaten 6-4 6-4 by Brazilian qualifier Beatriz Haddad Maia. The Spaniard has won just one match in two campaigns at Wimbledon since lifting the trophy.