Tsonga, Melzer land in Vienna quarters
{{#rendered}} {{/rendered}}Top seed Jo-Wilfried Tsonga and two-time round winners at Vienna's $790,000 Erste Bank Open.
The French Tsonga was leading Jarkko Nieminen 3-6, 6-1, 3-1 when the Finnish veteran retired due to a thigh injury on the indoor hardcourts at Wiener Stadthalle.
"It was difficult in the beginning, the first set was tough for me," Tsonga said. "Jarkko played well but he was not able to continue. It's like this in tennis a lot at the end of the year."
{{#rendered}} {{/rendered}}Nieminen was last week's runner-up in Stockholm.
Tsonga's quarterfinal opponent on Friday will be capable Belgian Xavier Malisse.
The third-seeded Melzer, meanwhile, continued his winning ways in Vienna with a 7-5, 6-1 handling of Spaniard Guillermo Garcia-Lopez.
{{#rendered}} {{/rendered}}Melzer defeated Andreas Haider-Maurer in last year's all-Austrian finale to claim a second straight championship at his home base.
Up next for the left-handed Melzer, who now has 20 match wins in Vienna, will be sixth-seeded African slugger Kevin Anderson.
A pair of upsets occurred on Day 4 when German Daniel Brands doused fourth- seeded Czech Radek Stepanek 6-4, 7-6 (7-4) and Malisse overcame eighth-seeded Italian Fabio Fognini 6-7 (3-7), 6-3, 6-3.
{{#rendered}} {{/rendered}}Other second-round action saw Belgian Steve Darcis drub Austrian wild card Dominic Thiem 6-2, 6-2 and former world No. 2 Tommy Haas came from behind to beat fellow qualifier Aljaz Bedene of Slovenia 4-6, 6-4, 6-1. The 33-year-old qualifier Haas was the Vienna champion in 2001 and runner-up in 2000.
The German Haas should have his hands full with second-seeded former U.S. Open champion Juan Martin del Potro here on Friday, when the oft-injured Haas will compete in his first ATP quarterfinal in 26 months.
One other quarterfinal will pit Brands against his fellow qualifier Darcis.
{{#rendered}} {{/rendered}}The 2011 Vienna titlist will collect $145,000.