Jo-Wilfried Tsonga claimed his first ATP Tour win since July at the Moselle Open, while Evgeny Donskoy booked a date with US Open finalist Daniil Medvedev at the St Petersburg Open.
After first-round defeats at the Rogers Cup and US Open, Tsonga this month dropped down to the Challenger Tour and won the Cassis Open without dropping a set.
The former world number five, a three-time champion in Metz, came from a set down to defeat Pablo Andujar 3-6 6-1 6-2 and set up a second-round clash with Pierre-Hugues Herbert, who downed eighth seed Jan-Lennard Struff 7-6 (7-3) 6-4.
Pablo Carreno Busta made light work of Julian Lenz, triumphing 6-1 6-1 in just 57 minutes, and the Spaniard will face top seed David Goffin in round two.
There were also wins for Richard Gasquet, Lorenzo Sonego, Gregoire Barrere and Aljaz Bedene.
Donskoy overcame Matteo Viola 6-2 6-1 in St Petersburg but can expect a far sterner test against world number four and fellow Russian Medvedev in the second round.
Andrey Rublev rallied from a set down and then a break down in the third to triumph 4-6 6-0 6-4 against Ilya Ivashka. Ricardas Berankis awaits him after overcoming Dudi Sela 6-3 6-0 in 62 minutes.
Roberto Carballes Baena downed 2012 champion Martin Klizan 6-2 7-5, while Egor Gerasimov beat Lukas Rosol 7-5 6-2 and Janko Tipsarevic retired while 7-5 3-6 3-1 down to Damir Dzumhur.