British number one Andy Murray cruised into the semi-finals of the Brisbane International with a 6-4 7-6 (7/3) win over Uzbekistan's Denis Istomin.
Murray served three aces in winning the first set, taking his only break point and saving two on his own serve.
The Scot served two double-faults at 3-4 in the second but kept his nerve to hold and remain on terms in the set. Istomin held after three deuces to lead 6-5 and the set continued to a tie-break with neither player facing a break point.
Istomin led 2-0 after an early point against the serve but Murray hit back to take the breaker 7/3 and set up a clash with Japan's Kei Nishikori, who beat Ukrainian Alexandr Dolgopolov by exactly the same scoreline, 6-4 7-6 (7/3).
The other semi-final will be contested by Grigor Dimitrov and Marcos Baghdatis, who both upset seeded players.
Dimitrov, from Bulgaria, served 17 aces in a 6-3 6-2 win over seventh-seeded Austrian Jurgen Melzer while Baghdatis, the Cypriot who reached the 2006 Australian Open final, beat French third seed Gilles Simon 6-3 6-4.
Women's top seed Victoria Azarenka was forced to pull out of her semi-final due to a toe injury, handing Serena Williams an automatic place in the final.
World number one Azarenka, from Belarus, reluctantly dropped out in order to regain fitness for the defence of her Australian Open title.
"Victoria has been nursing this injury for the past 10 days and it has continued to deteriorate to a point where she is unable to take to the court tonight," tournament director Cameron Pearson told brisbaneinternational.com.au.
"We wish her all the best with her recovery and we hope to see her in Melbourne to defend her Australian Open title."