No frills from Roger Federer in latest Qatar win

After thrilling the crowd on Tuesday with one of his between the legs trick shots, the Swiss world No 2 laboured to a 7-6, 7-5 victory in one hour 48 minutes.

Twice former champion Federer made little impression on his opponent's serve during a tight first set and trailed by a break in the second before recovering to clinch victory with a smash. It was far from vintage Federer, though, and the 16-times grand slam champion appeared to be playing within himself for long periods against a player he had beaten on their only previous meeting.

Third seed Jo Wilfried Tsonga of France, making his comeback from injury, moved into the quarter-finals with a 6-2, 6-4 defeat of Ukraine's Sergei Bubka.

In Auckland, meanwhile, Briton Heather Watson produced an upset at the ASB Classic by knocking out ninth seed Carla Suarez Navarro.

In doing so, the 18-year-old from Guernsey - playing as a qualifier in New Zealand - reached her first WTA Tour quarter-final, where she will meet China's Shuai Peng.

Watson was good value for her win, beating the Spaniard 7-6 (7/5), 6-1.

She was broken three times in the first before clinching it in the tie-break and world No 57 Navarro struggled in the second set as Watson capitalised on her momentum. "I'm so pumped to be in the quarter-finals here in Auckland!" Watson said on Twitter. "I played really well today."

Watson's compatriot, Anne Keothavong, was less inspired, losing 7-5 6-3 to wildcard Kateryna Bondarenko.