Nadal is the current World no 1 but withdrew from the Australian Open this week after a thigh injury.

The Spaniard exited at the quarter-final stage, meaning he will lose 840 ranking points after reaching the final in Melbourne last year.

If Roger Federer wins the Australian Open then the tables could be turned before the middle of March.

Nadal currently has 10600 points but that will drop to 9760 once Melbourne is complete.

Federer, on 9605 points, can only maintain that level if he wins in Australia.

That potential gap of 155 points could easily be overturned when they both play again in late February.

Nadal therefore needs to claim ranking points soon if he is to maintain his top spot heading into the summer.

And for that to happen he needs to win the Mexico Open.

Nadal reached the final in Acapulco last year, meaning he will be defending a valuable 30 points when he recovers from injury.

Should he win the ATP 500 event he will earn 500 ranking points.

But Federer us also playing an ATP 500 tournament in Dubai that week - and herein lies the problem for Nadal.

For is the Spaniard crashes or limps out of the Mexico Open in the early rounds, Federer could pounce.

For the Swiss is defending just 45 points in Dubai this year after exiting in only the second round in 2017.

That means Federer could get a 455-point boost in mid-March and feasibly overtake Nadal.