SYDNEY: Austrian top seed Dominic Thiem had a three-set struggle with Portuguese qualifier Gastao Elias before clinching a quarter-final spot at the Sydney International on Wednesday. Thiem, the world number eight, had several chances to put away the plucky 81st-ranked Elias, only to be broken back before he eventually won 6-7 (5/7), 6-3, 7-5 in a match that finished at midnight. Thiem will now face Britain’s number three Daniel Evans in Thursday’s quarters. Evans fought back from dropping the opening set to down Spanish eighth seed Marcel Granollers 1-6, 6-3, 6-3. Gilles Muller earlier beat the heat to be one match away from a third straight semi-final appearance at the Sydney International, following a big-serving victory over Australian Matt Barton.The sixth seed from Luxembourg prevailed over Barton 6-1, 3-6, 6-4 to reach the quarter-finals. Muller, who lost to Grigor Dimitrov in last year’s semi-final, will next face Uruguayan second seed Pablo Cuevas, who overcame Frenchman Nicolas Mahut 6-4, 2-6, 6-2. German fifth seed Philipp Kohlschreiber knocked out Australian Jordan Thompson 7-5, 6-4 and will face the two-time defending champion Viktor Troicki. Third seed Troicki from Serbia won his 13th consecutive match at the Sydney international with a 6-3, 6-4 win over Italy’s Paolo Lorenzi.