The Greek Stefanos Tsitsipas defeated Jan-Lennard Struff 7-6 (7-5) 6-4, while Daniil Medvedev battled back after losing the first set to beat Robin Haase, advancing to quarterfinals of the Sofia Open.

Fernando Verdasco also came through three sets, beating Marius Copil 6-2 4-6 6-1, and Gael Monfils cruised past Mikhail Kukushkin. There were also wins for Marton Fucsovics and Martin Klizan.

Meanwhile, Lucas Pouille was knocked out of the Open Sud de France on Thursday after the rest of the seeds all won in both Montpellier.

Top seed Pouille looked to be on course for a last-eight meeting with the unfancied Radu Albot as he took a commanding lead against Marcos Baghdatis in the late match on Court Patrice Dominguez.

But the French defending champion lost his grip on the first set and, despite battling back in the second, he could not reclaim control of the contest and Baghdatis can now target a place in the semis after a 7-6 (7-2) 6-7 (3-7) 6-4 win.

Albot lies in his way, having required three sets to get past the erratic Ernests Gulbis.

The other two seeds in action set up a clash of their own as both Denis Shapovalov and Pierre-Hugues Herbert won.

Shapovalov breezed past Marcel Granollers, while Herbert rallied after losing the first set to Ilya Ivashka, coming out on top 4-6 6-4 6-2.