CINCINNATI, OH, USA - No.4 seed Garbiñe Muguruza advanced to her first final at the Western & Southern Open on Saturday, with a comprehensive semifinal victory over World No.1 and defending champion Karolina Pliskova, 6-3, 6-2.

The odds were stacked against Muguruza on paper, as Pliskova was looking to become just the second player to defend her title in Cincinnati this week, and the Spaniard had won just one out of the previous seven meetings against the top seed. 

Nonetheless, Muguruza broke serve in the first game of the match to set the tone for the afternoon and never looked back to roll to victory in one hour, 19 minutes, capping the match by winning a marathon break on her fifth match point.

Muguruza scored her fourth win against a World No.1 with the victory, and third in straight sets, having previously defeated Serena Williams at Roland Garros in 2014 and also 2016. It is the Spaniard's second win over a No.1 player this year, as she beat Angelique Kerber in three sets en route to winning Wimbledon.

"To beat the player that is now No. 1, it's a very good match, always," Muguruza said after the match. "I felt pretty good out there and in control. Everything was going my way."

Muguruza's forehand in particular was firing throughout the course of the semifinal encounter, while she broke the big-serving World No.1 four times in the match.

A break in the first game on her fourth opportunity set the tone for Muguruza - she converted on four of the 14 chances she generated in the match - and added an insurance break in the ninth game to wrap up a set where she was never taken to deuce on serve.

Though both players struck nine winners in the opening set, Pliskova was undone by 14 unforced errors, more than twice the five that came off Muguruza's racquet.

"Today I think I was very precise with my shots. I also played very well," Muguruza said. "I wanted just to be more aggressive, trying to take my shots, and not think a lot about her, because I know she played very aggressive, as well. I'm working hard on trying to face these aggressive opponents, so today I felt a little bit better.

The second set began with another lengthy service game, but this time it was the Spaniard who was challenged on serve for the first time in the match. In a five-deuce game, Pliskova created her first break points of the match, but was unable to win any of her three chances as Muguruza kept her lead.

"I wasn't panicking at any moment, because I know she she returns very well," Muguruza said of that game. "I knew I was going to be in danger at some point, so I stayed calm. I managed to not lose courage, and I turned it around."

The first five games of the second set went with serve before the Wimbledon champion made her move, breaking the Pliskova serve to 15 as she ran off the last four games of the match to reach her first final in Cincinnati.

Pliskova, meanwhile, will see her current brief spell at World No.1 come to an end if Simona Halep wins the title against Muguruza on Sunday, as she looks toward defending last year's runner-up showing at the US Open.

"I don't think I played my best tennis today. I think the energy was pretty low from my side," said the Czech in defeat. "Obviously, it was a tough schedule for me in the last two days: three matches in about not even 24 hours.

"I think she played very solid today, not missing much and obviously serving well. The percentage from her side was pretty high, as well. Everything started, I think even in the first game of the first set, my serve, and then obviously the second game. I had some chances in the second set. Tough to find something positive on this match, but overall I think in the last couple of days or weeks, I had some good matches and some good days."