ROTTERDAM, Netherlands (AFP) — Roger Federer will target a return to the top of the rankings as the Rotterdam World Tennis tournament starts on Monday, with the Swiss aiming to become the oldest number one player in ATP history.

The test begins at the Ahoy stadium when the 36-year-old, who claimed his 20th Grand Slam title a fortnight ago in Melbourne, returns to the Dutch port city for the first time since 2013.

Top seed Federer starts in the first round against a qualifier in an event he has won twice before, lifting the trophy in 2005 and 2012.

Should he reach the semi-finals, Federer would pass Rafael Nadal to take over the world’s top ranking.

But his quarter-final opponent could well be long-time friend Stan Wawrinka, seeded fifth as he comes back from 2017 knee surgery.

Federer lies just 155 points behind the injured Nadal in the standings, with a possible 180 points available for making the last four in Rotterdam.

The Swiss would surpass Andre Agassi, who held the top spot in 2003 aged 33 years and 131 days.

The evergreen Federer has repeatedly said he has no intention of stopping in the foreseeable future, but realises that maintaining his longevity requires his trademark precise planning, of which the decision to compete in Rotterdam is the latest example.

“I’ve won three slams now in 12 months. I can’t believe it myself. I just got to keep a good schedule, stay hungry, then maybe good things can happen.

“I don’t think age is an issue, per se. It’s just a number,” he said after winning the Melbourne title for a sixth time.

“But I need to be very careful in my planning, really decide beforehand what are my goals, what are my priorities. I think that’s what’s going to dictate how successful I will be.”

Out to stop the Federer progress will be second seed Grigor Dimitrov, winner of the London year-end showpiece in November and an Australian Open quarter-finalist.

“The more top players, the better it is,” Dimitrov said of Federer’s presence. “You want to play the top players in the clutch matches.

“That’s what I’m here for – to compete, it’s why we play tennis.”

Dimitrov faces Japan’s Yuichi Sugita in the first round, while rising German Alexander Zverev takes on Spanish veteran David Ferrer.

Belgium’s David Goffin is seeded fourth ahead of Wawrinka. 2014 champion Tomas Berdych is sixth and Frenchman Lucas Pouille stands seventh.

Jo-Wilfried Tsonga, the defending champion, injured a hamstring in Saturday’s Montpellier semi-finals and will be unable to take his place in the field, while Nick Kyrgios was forced out by an elbow problem.