Top seed Marin Cilic of Croatia saved three match points in a third-set tiebreaker against Igor Sijsling of the Netherlands to advance to the quarterfinals of the U.S. National Indoor Championships with a 7-6 (2), 3-6, 7-6 (7) victory Thursday.
Cilic, the world's 12th-ranked player, battled Sijsling for more than 2 1/2 hours and saved four break points in the 11th game of the third set to take a 6-5 lead. Cilic squandered a match point with Sijsling serving at 5-6 in the third set.
In the tiebreaker, Sijsling double-faulted on his third match point of the tiebreaker and lost the match when he netted a forehand from behind the baseline.
The win moved Cilic, who won his ninth ATP Tour title two weeks ago in Zagreb, into the quarterfinals against fifth seeded Kei Nishikori of Japan, who advanced with a 6-3, 6-3 victory over qualifier Donald Young of the U.S.
Also moving into the quarterfinals were No. 7 seed Alexandr Dolgopolov of Ukraine, Denis Istomin of Uzbekistan and American Michael Russell.
Dolgopolov beat American qualifier Rhyne Williams 6-4, 4-6, 6-4; Istomin defeated former world No. 1 Lleyton Hewitt of Australia 6-1, 6-2 and Russell won 6-2, 6-4 over Lukasz Kulbot of Poland.
No. 4 seed Sam Querrey and sixth-seeded Tommy Haas of Germany play their second-round matches later on Thursday.
Earlier Thursday in the women's quarterfinals of the tournament, top-seeded Kristen Flipkens of Belgium was eliminated by Magdalena Rybarikova of Slovakia, the No. 7 seed, 6-7 (11), 7-5, 6-3.
Flipkens' loss meant the tournament's top two seeds in the women's draw are eliminated. Second-seeded Sofia Arvidsson lost her second-round match to Marina Erakovic on Wednesday.
And fourth-seeded Heather Watson of Britain also lost on Thursday, eliminated 6-1, 6-2 by Stefanie Voegele of Switzerland.
That left Sabine Lisicki of Germany as the only player of the top half of the draw to move on to the semifinals as she defeated eighth-seeded Kristina Mladenovic with a 6-3, 6-3 win.
In Friday's semifinals, Voegele will play Erakovic of New Zealand, a 7-5, 6-2 winner over Jamie Hampton of the United States on Thursday, while Lisicki and Rybarikova will face off in the other match.