'Fighter' Kartal stuns Keys in Indian Wells comeback

Kartal said she will prioritise recovery for her back before she meets Kazakhstan's Elena Rybakina, the reigning Australian Open champion, in the last 16.

"It [the back] was a pretty big hindrance," Kartal added.

"I didn't really practise yesterday so I gave it as much recovery as I could, so I think now it's about getting recovered and doing the same exact thing to get back on the court in the next couple of days."

Kartal was not the only player to cause an upset on Monday with a comeback win.

Czech Katerina Siniakova, the world number 44, knocked out defending champion and Russian eighth seed Mirra Andreeva in a gruelling 4-6 7-6 (7-5) 6-3 win that lasted two hours and 48 minutes.

Meanwhile, third seed Rybakina claimed her fourth-round spot with a hard-fought 6-4 6-4 victory over Ukraine's Marta Kostyuk.

World number two Iga Swiatek, the reigning Wimbledon champion, overcame Greece's Maria Sakkari, while American fifth seed Jessica Pegula fought back from a set down against Jelena Ostapenko to reach the last 16.