MIAMI (REUTERS) - The early action at the Miami Open quarter-finals was cut short on Wednesday (March 30), when Spain's Paula Badosa retired from her match against Jessica Pegula and Italian ninth seed Jannik Sinner did the same versus Francisco Cerundolo.

Officials said that Badosa had a viral illness, while Sinner called it quits as a result of foot blisters. Both were favourites to advance and retired at 4-1 down in the first set of their respective matches.

Pegula, who will feature in her second WTA 1000 semi-final, lost her serve in the first game but immediately broke back, before converting again in the fourth game, dropping just one of 10 first-serve points in her limited time on the court.

"I don't think I really thought she was going to retire, like maybe not that quickly, maybe a set or, if anything, but not that soon," the American told reporters.

Pegula, who reached her second consecutive Australian Open quarter-final this year, will face the winner of a match between 2020 Roland Garros winner Iga Swiatek and twice Wimbledon champion Petra Kvitova.

"Been struggling with illness since the last match the other day. Tried everything to recover but wasn't enough. I'll take some days to recover well and prepare for clay court season," Badosa wrote on Twitter.

Sinner's nightmare blisters meant Cerundolo's dream run continued, as he reached the semi-final in his first Masters 1000 main draw.

The 103rd-ranked Argentine battled past Americans Reilly Opelka and Frances Tiafoe and Frenchman Gael Monfils earlier in the tournament and now faces the victor of a meeting between fourth-ranked Alexander Zverev and world No. 8 Casper Ruud.

"It's everything (I've) dreamed of," the 23-year-old said.