TORONTO -- Caroline Wozniacki outlasted top-ranked Karolina Pliskova 7-5, 6-7 (3), 6-4 in a marathon women's quarter-final Friday at the Rogers Cup.

The start of the match was delayed for over two hours due to rain and three more weather interruptions followed once play began at Aviva Centre.

In the deciding set, Wozniacki broke at love to get back on serve at 4-4. She held serve and followed with another break to reach the final four at the Toronto event for the first time.

The match ended just over five hours after the players took to the court in the early afternoon for the pre-game warmup. Actual match time was two hours 56 minutes.

Pliskova, from the Czech Republic, was playing her first tournament as world No. 1. Wozniacki spent 67 weeks as the world's top-ranked player in 2010 and 2011 but her ranking has slipped over the last two seasons due to injuries.

Defending champion and second seed Simona Halep of Romania was scheduled to play Caroline Garcia of France on Friday night.

In the other quarter-finals, American Sloane Stephens was to meet Lucie Safarova of the Czech Republic and fifth-seeded Elina Svitolina of Ukraine was to take on fourth-seeded Spaniard Garbine Muguruza.

Wozniacki won the 2010 Rogers Cup in Montreal and returned to the semifinals there in 2012.

After dropping the first three games of the opening set Friday, Wozniacki fought back by beating Pliskova at her own game. She matched her powerful ground strokes and used a more aggressive style to take the momentum.

On her heels a bit more, Pliskova's unforced errors started to rise. She smashed her racket into the court when another miscue gave Wozniacki a 6-5 edge.

The Dane used an ace to win her sixth straight game and the first set.

Both players held serve through the second set with Pliskova pulling even in the match by taking the last four points of the tiebreaker.

Pliskova used a strong backhand cross-court to earn the first break of the third set. She pulled ahead 3-2 as Wozniacki was forced wide and netted her return.

However, Wozniacki refused to buckle and breaks in two of the last three games gave her a semifinal berth and a 5-2 career head-to-head mark against Pliskova.

The lone Canadian left in the doubles draw was set to play later Friday. Ottawa's Gabriela Dabrowski and Latvia's Jelena Ostapenko were to take on the third-seeded duo of Safarova and Barbora Strycova of the Czech Republic.

In early doubles matches, top-seeded Russians Ekaterina Makarova and Elena Vesnina beat Lyudmyla Kichenok of Ukraine and American Nicole Melichar 6-4, 6-4. Second-seeded Yung-Jan Chan of Taiwan and Switzerland's Martina Hingis dropped a 6-4, 6-4 decision to eighth-seeded Anna-Lena Groenefeld of Germany and Kveta Peschke of the Czech Republic.

Play continues at the US$2.74-million tournament through Sunday.