The 20-time major winner will leapfrog Rafael Nadal at top of the ATP rankings if he reaches the semi-finals of the tournament in the Netherlands.
Roger Federer targets No 1 spot after announcing he will compete in Rotterdam
Roger Federer will bid to replace Rafael Nadal as world No 1 when he competes in Rotterdam next week.
The 36-year-old Swiss won his sixth Australian Open title and 20th grand slam in January and reaching the semi-finals of the Rotterdam Open in the Netherlands would return him to top spot in the ATP rankings for the first time since November 2012.
Nadal is not set to play before the end of February at the earliest as he recovers from injury that forced him to retire from his quarter-final with Marin Cilic at the Australian Open in the final set.
He would also surpass Andre Agassi as the oldest ever world No 1 - the American was 33 when his sixth stint at the summit of men's tennis ended in September 2003.
Federer, who won the event in 2005 and 2012, told his official website: "The tournament is special for me.
"I remember playing for the first time in 1999 as it was one of the first events where I got the chance to play at the highest level. It feels good to join in the celebrations of the 45th edition."
Federer last played the event in 2013 when he was beaten in the quarter-finals by Julian Benneteau.
His 2005 title was won by beating Ivan Ljubicic in the final, while in 2012 it was Juan Martin del Potro who he defeated to be crowned champion.
Stan Wawrinka, Grigor Dimitrov, Alexander Zverev and defending champion Jo-Wilfried Tsonga are also due to compete in Rotterdam.