Halep, Kerber battle through to semis

Doha, AFP: World number three Simona Halep and three-time Grand Slam champion Angelique Kerber came through tough tests on Thursday to reach the Qatar Open semifinals.

Also through are Elina Svitolina and Elise Mertens, providing some comfort for tournament organisers who have somehow ended up with three of the world's top 10 in the last four, despite a high number of prominent withdrawals.

Halep won in straight sets but needed two tie-breaks -- 7-6 (7/1), 7-6 (8/6) -- to edge past Germany's Julia Goerges, despite racing to a 4-0 lead in the first set.

However, the match turned out to be anything but routine for the Romanian who was forced to save two set points and break Goerges' serve in the 10th game to stay in the second set.

The Romanian will play Svitolina, ranked seventh in the world, in the last four on Friday.S

Svitolina was the first player through to the semifinals, beating Czech qualifier Karolina Muchova by contrast in easy fashion 6-4, 6-2.

She was followed on court by Kerber, the world number six, who won 1-6, 6-2, 7-6 (7/4) in a tough and feisty encounter against another Czech, Barbora Strycova, who was given a time violation in the final set.

Kerber will play Belgium's Mertens, the world number 21, in the last four, who beat Kiki Bertens of the Netherlands 6-4, 6-3.

Nishikori in quarters

Japan's Kei Nishikori carved out a comfortable 6-1, 6-4 win over Latvian Ernests Gulbis on Thursday to power into the Rotterdam Open quarterfinals.

Nishikori will on Friday meet Hungarian Marton Fucsovics, who defeated Nikoloz Basilashvili of Georgia 7-6 (7/1), 6-1, for a place in the semifinals.

Earlier, Jo-Wilfried Tsonga won a lengthy opening set and then accelerated past Dutchman Tallon Griekspoor for a quarter-final place.

The Frenchman's 7-6 (7/5), 6-1 victory was a match of two parts, with the laborious first set taking 53 minutes while the second lasted just 23.

Tsonga, the 2017 champion in Rotterdam, will keep up his bid for a second straight trophy after winning Montpellier at the weekend as he continues his comeback from a seven-month absence last season due to knee surgery and recovery.

Tsonga next faces fifth-seeded Russian Daniil Medvedev who defeated Spanish veteran Fernando Verdasco for the second time in three meetings, posting a 6-2, 7-5 win.

Bosnian Damir Dzumhur followed up on his second-round upset of third seed Stefanos Tsitsipas, advancing past Kazakh Mikhail Kukushkin 6-4, 7-6 (7/3).

Jung upsets Tiafore

Seven months after his Grand Slam debut, journeyman Jason Jung recorded the biggest scalp of his career when he upset Frances Tiafoe 6-3, 7-5 in the second round at the New York Open on Thursday.