Azarenka battles past Putintseva into Miami semis

The 34-year-old Azarenka, who won in Miami in 2009, 2011 and 2016, had to deal not only with the spirited display from the Moscow-born Kazakh player, but also a long disruption to the match due to a technical problem.

The match was stopped for 45 minutes in the fourth game of the first set due to a power outage which impacted the umpire's communications and the hawkeye system.

Azarenka had to save three set points on Putintseva's serve at 5-4 in the first set, then missed out on two set points of her own at 6-5 before the tie-break.

Putintseva dominated the second set but Azarenka found the strength to get ahead in the third but still her opponent refused to relent, fighting off match point before breaking.

But Azarenka held on her next serve to secure passage to the last four and keep alive her hope of a fourth Miami title.

"Yulia played great, she's in such great form and I really had to dig deep. I felt like my legs were kind of giving in a little bit and I lost a little bit of self-belief because she was playing so well and moving me around everywhere," said Azarenka.

"But I'm happy that I was able to regroup, reset and really take my chances, come out and play aggressive and face the challenge," she said.

Azarenka said the win showed that there can be no doubt about her desire to compete at the highest level.

"I'm motivated to compete and go after my dreams. I've been playing on tour for 20 years and I still feel like I am improving, that's priceless for me and I want to keep going," she added.

Later on Tuesday, eight seed Maria Sakkari faces fourth seed Elena Rybakina, the highest seeded player left in the tournament.

World number one Iga Swiatek, Aryna Sabalenka and third seed Coco Gauff have all been eliminated in Miami.