Diego Schwartzman saved four match points to edge Pablo Cuevas in the Argentina Open quarter-finals.
Dan Evans was unable to stop Gael Monfils in his tracks at the Rotterdam Open.
Illness forced Petra Kvitova to withdraw at the St Petersburg Ladies Trophy, while defending champion Kiki Bertens reached the semi-finals.
Jordan Thompson overcame big-serving American John Isner – who had a first-round bye – 7-6 (7-2) 6-7 (3-7) 6-3 in New York on Thursday.
Daniil Medvedev was followed out of the Rotterdam Open by Stefanos Tsitsipas and David Goffin on Thursday.
Petra Kvitova had to slog her way into the quarter-finals in St Petersburg but Kiki Bertens was in scintillating form.
Kwon Soon-woo weathered 33 aces from Milos Raonic as the South Korean prevailed after two hours, 25 minutes midweek.
Daniil Medvedev lost in the first round of the Rotterdam Open, with Roberto Bautista Agut and Grigor Dimitrov also losing on Wednesday.
Johanna Konta was the biggest name to lose in St Petersburg, where Belinda Bencic booked her place in the last eight.
Garbine Muguruza has joined the field at the Dubai Tennis Championships, but Bianca Andreescu has pulled out of the WTA Tour event.
The 20th annual Laureus World Sports Awards will take place on Monday in Berlin, with Lionel Messi and Liverpool in the hunt.
Garbine Muguruza battled to victory against Kim Clijsters, who was playing her first competitive match for more than seven years.
Daniil Medvedev is next for Jannik Sinner after he overcame Norbert Gombos in straight sets in Marseille.
Australian Open runner-up Dominic Thiem returned to action with a win in Rio de Janeiro.