World No. 1 Novak Djokovic won another gruelling battle in Doha on Thursday to continue his unbeaten start to the year and progress to the Qatar Open semifinals.

The Serb came from a set down, just like in his previous match, to beat Georgia's Nikoloz Basilashvili 4-6, 6-3, 6-4 in a match lasting almost two hours.

Djokovic will play Spain's Roberto Bautista Agut in Friday's semifinal, who beat three-time Grand Slam winner Stan Wawrinka in straight sets 6-4, 6-4.

It was the first time Djokovic has won back-to-back matches from a set down since Cincinnati in August last year, a tournament he went on to win.

Also through to the semifinals is Tomas Berdych of the Czech Republic who brushed aside France's Pierre-Hugues Herbert 6-2, 6-4.

The last semifinal spot went to Italy's Marco Cecchinato who beat Dusan Lajovic of Serbia 7-6 (7/2), 6-2.