Roger Federer began his quest to reclaim the world No 1 ranking with a ruthless straight-sets demolition victory over Ruben Bemelmans at Rotterdam’s ABN Amro World Tennis Tournament.
The world No 2, who needs to reach the semi-finals to replace Rafael Nadal and also become the oldest player at the summit of men's tennis, marked his return to competitive action after winning the Australian Open last month with a 6-1 6-2 victory.
Federer, a two-time champion in Rotterdam, accepted a wildcard to feature in the 500 event and will next meet German veteran Philipp Kohlschreiberin the last 16.
The 36-year-old top seed broke twice in the first set against the Belgian qualifier and secured the opener with a trademark forehand winner.
Bemelmans was broken in his opening service game of the second set and despite offering some resistance was unable to threaten a dominant Federer, who claimed victory in the pair's first meeting in 46 minutes.
Second seed Grigor Dimitrov recovered from a break deficit in the second set to secure a 6-4 7-6(5) victory against Yuichi Sugita in their first-round meeting.
The Bulgarian proved too strong for Japan's world No 41 in a match which lasted one hour and 46 minutes and he will next meet Filip Krajinovic.
Alexander Zverev, world No 4, suffered a surprise 6-4 6-3 defeat to lucky loser Andreas Seppi, who secured his first victory over a top 10 player since the Italian defeated Federer at the Australian Open in 2015.
Last year's ATP Finals runner-up David Goffin cruised to a 6-1 6-3 against Feliciano Lopez in his second match of the week.
The Belgian world No 7 will face Tomas Berdych in the last eight after the experienced Czech player defeated Viktor Troicki 6-1 6-2.
The opening match of Wednesday's schedule saw Lucas Pouille, who came into the tournament on the back of winning the Open Sud de France title last week, broken four times in a 7-5 6-4 defeat by talented Russian Andrey Rublev.
Robin Haase prevailed in a meeting between two Dutch players as the world No 42 eased past wildcard compatriot Thiemo de Bakker 6-2 6-2 to reach the last 16, where he will meet another countryman in wildcard Tallon Griekspoor.
The 20-year-old will next meet Damir Dzumhur after the world No 29 overcame Marius Copil, runner-up in Sofia last week, 6-4 6-4.
Qualifier Pierre-Hugues Herbert benefited from an early retirement by countryman Richard Gasquet at 3-1 to help him earn a last 16 meeting with Daniil Medvedev.