WTA Finals: Angelique Kerber has the keys

Dominika Cibulkova celebrates after defeating Simona Halep in the quarters of the WTA Finals on Thursday. (Photo: AFP)

Germany’s Angelique Kerber continued her unbeaten run at the WTA Finals on Thursday, steamrolling rising American Madison Keys 6-3, 6-3 to charge into the semi-finals of the season-ending championship.

Still on a high after winning the US Open last month, the newly crowned world number one made it three wins on the trot at Singapore’s Indoor Stadium to finish at the top of the Red Group standings after the round-robin phase.

Kerber was joined in the semis by Slovakia’s Dominika Cibulkova, who claimed her first victory of the tournament by defeating Simona Halep of Romania 6-3, 7-6 (7-5), to finish as the group runner-up.

Cibulkova will play Svetlana Kuznetsova in Saturday’s semis after the Russian finished top of the White Group. Kerber will meet with either the defending champion, Agnieszka Radwanska, or US Open finalist Karolina Pliskova, who meet on Friday to decide the last available spot.

Murray survives Klizan scare Vienna: Andy Murray’s pursuit of the world number one ranking was severely tested by Slovak left-hander Martin Klizan in his Vienna opener on Wednesday before the British star clinched a 6-3, 6-7 (5/7), 6-0 win.

Murray will face Frenchman Gilles Simon in the next round with a 15-2 career record.

Big-hitting John Isner of the United States hit 52 winners and 31 aces in a 7-6 (7/1), 3-6, 7-6 (7/2) victory over 2004 champion Feliciano Lopez to reach the quarterfinals.

Ivo Karlovic of Croatia is also into the last-eight after 33 aces took him to a 7-6 (8/6), 4-6, 7-6 (7/5) win over Damir Dzumhur of Bosnia.

Nishikori powers through Basel: Kei Nishikori dominated Paolo Lorenzi 7-6 (7/3), 6-2 to reach the Swiss Indoors quarterfinals on Wednesday, with Asia’s top player feeling his way back after a series of recent fitness problems.

Two-time champion Juan Martin del Potro continued his run of form after winning Stockholm, with the champion in Sweden starting his Swiss week with a 6-3, 6-4 defeat of injured Robin Haase.

Argentine Guido Pella advanced as French seventh seed Richard Gasquet retired injured trailing 6-2, 2-1.

American eighth seed Jack Sock eliminated Frenchman Adrian Mannarino 6-3, 6-3 while Pablo Carreno Busta won an all-Spanish showdown over Fernando Verdasco, 7-5, 6-3. Germany’s Mischa Zverev defeated US teenager Taylor Fritz 7-6 (7/4), 6-0.