Eight-time champion Serena Williams has withdrawn from the Miami Open because of a knee injury.
American Williams reached the third round on Friday by beating Sweden’s Rebecca Peterson, only the seventh match she has completed in 2019.
The 23-time Grand Slam winner was set to face Wang Qiang in the last 32 but the Chinese 27-year-old now gets a bye.
World number one Naomi Osaka suffered a shock three-set loss to Hsieh Su-wei, ranked 27th, in their third-round tie.
Williams, who said she was “disappointed”, has now withdrawn from two consecutive WTA events, following her retirement from last week’s tournament in Indian Wells because of a viral illness.
The 37-year-old last claimed the Miami title in 2015, with her last Grand Slam win coming at the 2017 Australian Open, a triumph which moved her one behind Margaret Court’s record of 24 major singles titles.
“I hope to be back next year to play at this one-of-a-kind tournament in front of the incredible fans here in Miami,” she said.
Japan’s Osaka, 21, has won the past two Grand Slam tournaments – the 2018 US Open and the Australian Open in January – but went down 4-6 7-6 (9-7) 6-3 to Hsieh on Saturday.
“This was a very emotional win for me,” said the 33-year-old Taiwanese, who will now face either Caroline Wozniacki of Denmark or Romanian Monica Niculescu in the fourth round.
“Any time you beat one of the top players it is amazing.”
World number two Petra Kvitova was tested by Croat Donna Vekic but won 6-4 3-6 6-4 to reach round four.
The Czech two-time Wimbledon champion and third seed had to fight for more than two hours against Vekic.
She will now meet France’s Caroline Garcia in the fourth round. Garcia beat German 15th seed Julia Gorges 6-0 7-5.
Indian Wells champion Bianca Andreescu beat eighth seed and world number four Angelique Kerber of Germany for the second time in a week.
The Canadian, who beat Kerber to win her maiden WTA title last Sunday, won 6-4 4-6 6-1 and extended her winning streak to 10 matches.
Federer fights back to avoid upset in Miami
Roger Federer rallied from a set down to beat Moldovan surprise package Radu Albot in a stuttering start to the 20-times Grand Slam champion’s Miami Open campaign.
Federer, beaten by Dominic Thiem in last week’s BNP Paribas Open final, smashed 14 aces and broke Albot twice to advance to the third round 4-6 7-5 6-3.
But it was far from plain sailing for the 37-year-old against the world number 46 in the match which lasted two hours and 10 minutes.
After dropping the first set, Federer broke Albot while leading 6-5 in the second with a backhand volley winner.
Albot could not convert a break point in the deciding set tied at 3-3, and the Swiss took command from there to wrap up the match.
Three-times Miami champion Federer finished with 38 winners but had to overcome 41 unforced errors to defeat Albot, who earned an ovation from the crowd for his efforts.