Alexander Zverev extended his winning streak to six in a row over Marin Cilic as the German made a fine start to his campaign at the ATP Finals in London.
Third seed Zverev sealed a 7-6 (7-5) 7-6 (7-1) victory in a tight contest over the Croatian to move top of Group Guga Kuerten on Monday.
He initially found himself trailing the 2014 US Open champion 3-0 and showed a touch of petulance by slapping down his racket in frustration.
Zverev, who has been suffering from a shoulder injury that has dogged him during the European indoor season, got on the board in the next game and then rallied to win four out of the next five games to level things up at 5-5 before the next two were held before heading into a tie-break.
Cilic made an inauspicious start to it, but despite a mini-fightback, the 21-year-old German wrapped it up with his third set point after 65 minutes.
This was the duo’s seventh meeting in three years, with Cilic looking to stop the German wunderkind from making it six wins on the bounce. They traded service games at the business end of the second set before former Wimbledon finalist Cilic saved a match point before heading into another tie-break.
Zverev took total control to claim victory, while the Croatian now has an unwanted 1-9 losing record at the tournament.