Novak Djokovic came back from a double break down in the final set to beat Belgian David Goffin and reach the last eight at the Cincinnati Masters.
Goffin, ranked 14th, looked on course for victory at 3-0 in the decider but world number one Djokovic took six straight games to win 6-4 2-6 6-3.
Britain's second seed Andy Murray takes on Bulgarian Grigor Dimitrov in the third round later on Thursday.
Top seed Serena Williams beat Karin Knapp 6-0 6-2 in the women's event.
Switzerland's Belinda Benic , who beat Williams on her way to winning the Toronto title last week, earlier retired with a right forearm injury when trailing Czech seventh seed Lucie Safarova 6-2.