Victoria Azarenka kept her hopes of a fourth Miami Open title alive as she reached the semi-finals with a hard-earned victory over Yulia Putintseva. (More Tennis News)

The number 27 seed, a winner here in 2009, 2011 and 2016, laboured for just under three hours as she battled past her Kazakhstani opponent 7-6 (4) 1-6 6-3.

The 34-year-old saved three set points at 5-4 down in the opening set, then failed to convert two of her own before she held her nerve in the tie-break with some decisive forehands.

Putintseva hit back hard in the second, giving up a solitary game as she found her rhythm, but the momentum shifted when Azarenka salvaged a pair of break points at the start of the decider.

After regaining control she did not take advantage of her first match point at 5-2 up, but made no mistake when the chance opened up again in her next service game.

Azarenka will face another Kazakhstani opponent in the last four after Elena Rybakina outlasted eighth seed Maria Sakkari in another marathon clash 7-5 6-7 (4) 6-4.

The fourth seed, runner-up in 2023, won the first set with a late break before Sakkari – who reached the final in Indian Wells last week – survived two match points to edge a tight second set on the tie break.

But Rybakina, who had already gone the distance twice in Miami, broke in the seventh game of the decider and served out to win – more than an hour after her first match points.

“I have no words because I’m so tired. But I’m really happy with the win. It was such a tough battle,” said Rybakina after clinching the win in two hours and 48 minutes.