The Swiss player reached last 16 in the Netherlands and only needs two more wins to leapfrog Rafael Nadal at top of the ATP rankings
Roger Federer still on track to go to world No 1 in Rotterdam
Roger Federer is just two wins away from becoming the world No 1 again after a first-round win at Rotterdam's ABN Amro World Tennis Tournament.
The 36-year-old Swiss was last at the top of the ATP rankings over five years ago and will return to that position by displacing Rafael Nadal if he makes it to the semi-finals.
He began his quest to become the oldest man to ever be world number one with a comfortable 6-1, 6-2 victory over Ruben Bemelmans in the first round on Wednesday.
"(It was) very surprising how good things went today," Federer admitted on atpworldtour.com.
"I think the key was to start off well and put Ruben under pressure right away and make him feel like he had to do something special."
Federer will play Philipp Kohlschreiber in the round-of-16 on Thursday.
Second seed Grigor Dimitrov advanced courtesy of a 6-4, 7-6 triumph over Yuichi Sugita, but third seed Alexander Zverev was knocked out in straight sets by Andreas Seppi.
Tomas Berdych and David Goffin also won, as did Robin Haase, who could face Federer in the quarter-finals.