Seven-times champion Serena Williams endured an unlikely scrap in her Wimbledon opener and will look to shake off more rust in the second round on Thursday when she faces another qualifier in 18-year-old Kaja Juvan.
Williams, who had been limited to seven matches since the Australian Open in January because of injuries, fought off 31-year-old Italian Giulia Gatto-Monticone 6-2 7-5 to progress.
The American, chasing a record-equalling 24th Grand Slam crown, could face another potentially tricky test against an opponent at the other end of the age spectrum.
“I think right now I have to have every match count, like 10 matches, because I haven’t had a ton of matches this year,” Williams told reporters.
“I learned a lot from that match, just going to keep the momentum going… to try to keep the edge… was important.”
Juvan, a singles and doubles gold medallist at last year’s Youth Olympic Games, will take inspiration from fellow teenager Cori Gauff who stunned Williams’s sister Venus in the opening round before beating Magdalena Rybarikova on Wednesday.
In other matches, double Wimbledon champion Petra Kvitova takes on France’s Kristina Mladenovic while French Open winner Ash Barty meets Alison Van Uytvanck of Belgium.
Australian Nick Kyrgios renews his rivalry with Rafa Nadal in a blockbuster second-round encounter on Centre Court while Roger Federer, who is on a quest to seal his ninth Wimbledon title, takes on Briton Jay Clarke.
Holder Angelique Kerber plays American Lauren Davis.