Cristiano Ronaldo has been an instant success in Serie A, and Giorgio Chiellini has compared him to Roger Federer and Usain Bolt.
Spanish veteran David Ferrer celebrated his 728th career win following Tuesday's victory against Malek Jaziri.
Having beaten Stan Wawrinka in the Rotterdam Open last year, Tallon Griekspoor added the scalp of world number 11 Karen Khachanov.
Julia Goerges dropped just four games en route to victory against Ajla Tomljanovic, while Kiki Bertens won a more difficult encounter.
Caroline Wozniacki pulled out of the Qatar Open due to illness on a day in which she was due to face Karolina Muchova in the first round.
There were contrasting fortunes for Bernard Tomic and Tennys Sandgren at the New York Open.
Milos Raonic or Philipp Kohlschreiber await Stan Wawrinka in the second round of the Rotterdam Open after he beat Benoit Paire.
Anastasija Sevastova or Anna Blinkova await Barbora Strycova in the Qatar Open second round after the Czech beat Fatma Al Nabhani.
Naomi Osaka enjoyed a breakthrough 2018 alongside coach Sascha Bajin but the two have parted ways.
Juan Ignacio Londero broke through for his first trophy as he outlasted countryman Guido Pella 3-6 7-5 6-1 in Cordoba on Sunday.