Roger Federer will usurp Rafael Nadal as the world number one if he beats Robin Haase in the quarter-finals at the ongoing ABN AMRO Open on Friday (16 February), but that has not stopped him from inviting the Spaniard to his hotel in Rotterdam.

The Spaniard is currently sidelined with a thigh injury and is not expected to play until the Mexico Open in Acapulco beginning on 26 February, but he is currently in the Netherlands to attend an event hosted by Hollywood star and environmentalist Leonardo DiCaprio.

Nadal was attending the Postcode Lottery Good Money Gala in Amsterdam on Thursday (15 February) and his presence just an hour away from Rotterdam caught the attention of his long-term rival, who could create history if he wins on Friday.

Federer has travelled to the Netherlands to play at the 45th edition of the Rotterdam Open without his family and thus invited the current world number one to visit since he is lonely without his wife and four children.

"He should come around. I'm lonely," Federer said when he learned that Nadal was in Amsterdam for the Gala, as quoted by the Express.

"My family is not here," the 20-time Grand Slam champion added.

Nadal and Federer's rivalry began when they first played each other at the Miami Open in 2004. They have since faced each other 38 times in the last 14 years and winning a combined 36 men's singles Grand Slam titles.

However, despite their long standing rivalry, they share a great relationship off the court. Federer was the guest of honour when Nadal opened his tennis academy in Mallorca in 2016 and they even paired up for the first time to play doubles in the Laver Cup when Team Europe took on Team World in September last year.

Roger Federer
Roger Federer could overtake Nadal as the world number one if he beats Robin Haase on Friday (16 February) Getty