MIAMI (AFP) -- Danielle Collins and Ekaterina Alexandrova will meet in the semifinals of the WTA Miami Open after victories in the last eight on Wednesday, March 27.

Collins powered into the last four with an emphatic 6-3, 6-2 win over France's Caroline Garcia before Alexandrova emerged triumphant from a near two-hour three set battle with American fifth seed Jessica Pegula.

Thursday will see the opening semifinal with three-time Miami winner Victoria Azarenka up against fourth-seeded Elena Rybakina, the highest ranked player left in the tournament.

Garcia went into the match against Collins on the back of an upset win over third-seeded American Coco Gauff but was unable to get a foothold against the Floridian.

Garcia still appeared to be troubled by an injury to her right shoulder and received some treatment early in the second set.

Collins broke to go 5-3 up in the first set and then held serve for the set, then in the second set broke in the third game and never looked back as she wrapped up the win in one hour and 19 minutes.

Collins reached the semifinals of Miami six years ago as a qualifier and at 53rd is the lowest ranked semifinalist in the tournament.

The 30-year-old American is now 4-0 against Garcia and has yet to lose a set to the Frenchwoman but said the numbers didn't tell the true story.

"I think against someone like Caro, it forces me to be more concentrated. I know I don't want to give her an inch or she can get in there," Collins said.

Garcia said she had felt the pace of back-to-back tournaments.

"It's been a long two weeks for the body for me, between the back at the beginning and then the she shoulder which came back," she told reporters, adding that the shoulder issue was a recurrence of a previous injury.

"I think it's nothing too serious but (shoulder) is always quite problematic for a tennis player," she said, before adding that Collins had played "an amazing match".

Collins intends to retire at the end of the year but while she agreed she had a relaxed look to her play, she rejected the idea that it was a result of her impending departure from the sport.

"I think I feel pretty relaxed, but that could be due to a number of things. I've got a new hobby. I'm playing some more golf, running more, Pilates, all of these different things," she said.

"My dog is here. I'm feeling relaxed because I get to be with him at night. I don't know," she said with a smile.

Home favorite

Alexandrova beat home favorite Pegula 3-6, 6-4, 6-4, showing plenty of grit in a third set where both players showed signs of fatigue.

Pegula broke to go 4-3 up in the first and broke again to clinch the set but the Russian fought back, breaking in the first game of the second set.

Again 14th seed Alexandrova broke early in the third but she let Pegula back into the set when she double-faulted on break point to leave the set balanced at 3-3.

The pair produced a fantastic rally in the subsequent game which Pegula was able to hold, but at 4-4, Alexandrova struck the decisive blow with Pegula going long on a back-hand return on the second break point.

The Russian held to grab the win and fell to her knees in joy at the result.

Alexandrova, who upset world number one Iga Swiatek in the previous round, said it was tough to break down Pegula's gritty defense.

"I couldn't understand how it was possible to return that ball it was always back. She was everywhere so I needed to do something," she said. "I tried to wait and use any opportunities that I got."

The win was Alexandrova's third against a top five player this year and she said her success was the result of developing patience.

"You have to wait and wait and something is going to come - and then you have to use it," she said.