World number 121 Ruben Bemelmans will be the first man standing between Roger Federer and his route to returning to world number one after the Belgian left-hander came through qualifying for the Rotterdam Open.

The 20-time grand slam champion Federer has to reach the semi-finals next week [12 February-18 Febraury] in order to eclipse Andre Agassi as the oldest man to top the ATP standings.

And that campaign will start against Bemelmans, after the 30-year-old won both of his weekend qualifying matches for the ABN AMRO World Tennis Tournament.

Bemelmans shocked Denis Istomin on Saturday [10 February] before beating home favourite Tim van Rijthoven 6-4 6-3 to reach the main draw.

Ranked a career-best 84 last October, Bemelmans has slipped outside the top 100 of late but did win his first ever match at the Australian Open last month, overcoming Lucas Pouille before being dumped out in the second round in straight sets by Nikoloz Basilashvili.

He has won 14 Challenger and Futures events, including in Koblenz, Germany earlier this year - his first title for 21 months. Bemelmans has never previously faced Federer in his 12-year professional career, but will duel with the Swiss legend on Wednesday [14 February].

Danill Medvedev, Martin Klizan and Pierre Hugues Herbert join Bemelmans in the main draw after also coming through the two-day qualifying event.

A lucky loser from the preliminary event will also be included in the main draw after defending champion Jo-Wilfried Tsonga was forced to pull out due to a suspected hamstring tear.

All eyes will be on Federer this week in Rotterdam as he attempts to add another slice of history to his already glittering CV.

Should Federer overcome Bemelmans he will be faced with either Karen Khachanov or Philipp Kohlschreiber in round two, before a possible clash with fellow-countryman Stan Wawrinka in the quarter-finals.

A last four berth will be good enough for Federer to replace Rafael Nadal at the summit of men's tennis however victory in his first appearance in Rotterdam since 2013 will be good enough to ensure he remains as world number one until the North American hard-court swing in March.

Ruben Bemelmans
Bemelmans faces arguably the biggest match of his career when he duels with Federer. Getty Images