Roger Federer is the new No.1 tennis player in the world.

The 36-year-old Australian Open champion will replace Rafael Nadal on Monday when the new rankings are released.

Federer beat Robin Haase 4-6, 6-1, 6-1 on Friday evening to reach the semi-finals of the ABN AMRO World Tennis Tournament.

The official ATP website reveals the 20 Grand Slam titles winner will be setting a host of records when he assumes the No.1 on Monday.

Federer will become the player with “the longest period between stints at No. 1, the oldest player to attain top spot and the longest duration between first and last days at the summit of men’s professional tennis.

After the quarterfinal victory, Federer was presented with a special award. “I think reaching No. 1 is one of, if not the ultimate achievement in our sport. So sometimes at the beginning you just all of a sudden get there just because you’re playing so well.

“Later you sometimes try to fight it back and you wrestle it back from somebody else who deserved to be there. And when you’re older, you know you feel like you have to put maybe sometimes double the work in.

“So this one maybe means the most to me [of any achievement] throughout my career, getting to No. 1 and enjoying it right here at 36, almost 37 years old. [It] is an absolute dream come true, I can’t believe it,” Federer added.

It is a dramatic return to the top for the Swiss player as he was ranked No.17 just 13 months ago.