Serena Williams tumbled out through injury while three Britons also fell by the wayside on day two.
Day three sees Andy Murray, Dan Evans and Katie Boulter in second-round action, while Cam Norrie has a first-round match to finish.
Defending men's champion Novak Djokovic opens things up on Centre Court against former runner-up Kevin Anderson.
Here, the PA news agency looks ahead to day three at Wimbledon.
Order of play
Novak Djokovic (1) v Kevin Anderson
Katie Boulter v Aryna Sabalenka (2)
Oscar Otte v Andy Murray
Elina Svitolina (3) v Alison Van Uytvanck
Dan Evans v Dusan Lajovic
Ons Jabeur (21) v Venus Williams
Match of the day
Boulter faces a huge test against second seed Sabalenka, but it is one the 24-year-old is likely to relish on Centre Court, especially after her battling three-set win over Danielle Lao in round one.
Has Novak found her yet?