Roger Federer will return to world number one for the first time in over five years after the 36-year-old defeated Robin Haase to reach the semi-finals of the Rotterdam Open.

After knee surgery in 2016, Federer's career has gone from strength to strength despite his advancing years, while his closest rivals all continue to struggle.

Starting with an unexpected triumph at last year's Australian Open, Federer has added another three grand slam titles to his tally – taking it to 20 – but regaining his spot at the top of the rankings had eluded him until now.

Novak Djokovic, Andy Murray and Rafael Nadal have all sat above Federer in recent years as the 'fab four' have dominated the men's game.

However, with Djokovic (elbow) and Murray (hip) both spending a significant amount of time on the sidelines it has become a straight battle with Nadal for top spot.

Injuries have not escaped Nadal, either, opening the door for the evergreen Federer to reclaim the world number one spot – a position he has not occupied since November 4, 2012.

Nadal's 2018 Australian Open ended in retirement at the quarter-final stage, while Federer went on to retain the crown, enabling him to close within 155 points of the Spaniard in the rankings, and after accepting a wildcard in Rotterdam, there has been another changing of the guard due to his run in the Netherlands.

REMEMBERING 2004

The achievement has come 14 years after he first became world number one, another prime example of Federer's longevity.

To emphasise that further, the top 10 Federer first reigned over looked like this….

1. Roger Federer
2. Juan Carlos Ferrero
3. Andy Roddick
4. Guillermo Coria
5. Andre Agassi
6. Rainer Schuttler
7. Carlos Moya
8. David Nalbandian
9. Mark Philippoussis
10. Paradorn Srichaphan

Not one of those names are still playing apart from Federer, although his long-term rival Nadal was beginning his own quest. Then just 17 years old, he ranked 40th.

On the WTA side, Justine Henin was the dominant player, enhanced by her own victory at Melbourne Park. Henin, who is 10 months younger than Federer, turned pro a year after the Swiss and retired in 2011.

ALL HAIL BRADY

Elsewhere in sport, it was also a momentous time for Tom Brady as he celebrated his second Super Bowl ring with the New England Patriots.

The quarter-back – who was denied a sixth title by the Philadelphia Eagles this month – threw 354 yards and three touchdowns in the Pats' 32-29 win over the Carolina Panthers.

Brady was named MVP after his display in a match that is equally well-remembered for Janet Jackson's wardrobe malfunction during the half-time performance with Justin Timberlake.

DOMINANT GUNNERS MARCH ON

As Federer sat on top of the world, Arsene Wenger's Arsenal were equally dominant in the Premier League.

In early February the Gunners were two points clear of Manchester United in the table, and it would go on to become one of the most memorable campaigns in their history.

Arsenal finished the 2003-04 season as champions, the last time they lifted the trophy, and as 'Invincibles', having completed the 38 matches unbeaten - a run that would stretch to an impressive 49 league games in total.

MILESTONES FOR WARNEY AND LEFTY 

A month later Shane Warne celebrated his 500th Test wicket, removing Sri Lanka's Hashan Tillakaratne in Galle – the Australia leg-spinner only the second man to reach the milestone.

April saw a momentous moment for another sporting icon as Phil 'Lefty' Mickelson finally lifted his first major, winning the Masters to claim the green jacket at Augusta.

Federer's year ended with him holding on to top spot after winning Wimbledon and the US Open. Should he repeat that feat this year he would move level with Steffi Graf on 22 grand slam singles titles.