The most eye-catching fixture of all on the opening day was the one between Dusan Lajovic and fifth seed Frances Tiafoe.
Spaniard Carreno Busta eased past Filip Krajinovic in straight sets to win the Hamburg European Open title.
Serbian Filip Krajinovic defeated the top seed Greek player in three sets to reach the semifinals of the Hamburg European Open.
The Serbian struck 31 winners to beat Cuevas in straight sets and will play Lithuania's Ricardas Berankis next in Paris.
On the back of his thumping victory at Belgrade Open, the Serbian has the fifth most Open Era wins list.
With an opening-round win in Belgrade, the Serbian has tied with Guillermo Vilas for the fifth-most wins in the Open Era.
After winning his match in straight sets, the Serbian World No.1 will take on Federico Coria in the last eight.