Seven-time champion Serena Williams' hopes of claiming a record-equalling 24th Grand Slam singles title at Wimbledon ended in tears as the American quit with an injury early in her first-round match against unseeded Belarusian Aliaksandra Sasnovich.
The 39-year-old needed treatment off the court when leading 3-2 in the first set and was clearly in distress on her return before being forced to retire at 3-3.
Her misfortune added to an already dramatic second day in which men's eight-time winner Roger Federer looked set for his first opening-round exit at a Grand Slam since 2003 when he found himself outplayed by Frenchman Adrian Mannarino.
The Swiss trailed by two sets to one but Mannarino slipped on the greasy Centre Court turf and although he soldiered on to lose the fourth set he could not continue.
Men's second seed Daniil Medvedev looked impressive as he came through a tricky opener against German powerhouse Jan-Lennard Struff, winning in four sets.
While many matches were cancelled because of rain, the roofs on Centre Court and Court One did their job to ensure continuous action.
Women's top seed Ash Barty opened the day on Centre with a 6-1 6-7(1) 6-1 victory over Carla Suarez Navarro who bade an emotional farewell to the tournament, having announced in April that she had recovered from cancer.
A long day concluded with her compatriot Nick Kyrgios locked in a late-night tussle with Frenchman Ugo Humbert on Court One.
The score was 3-3 in the fifth set when play was suspended just before 11pm local time -- the cut-off for play.
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