Roger Federer's participation in the Dubai Tennis Championships remains shrouded in mystery after the 20-time grand slam champion updated his upcoming schedule for the 2018 season via his official website.

The 36-year-old is in hot pursuit of world number one Rafael Nadal after winning the Australian Open last month and can become the oldest man to top the ATP standings if he wins the event in the United Arab Emirates, which begins on 19 February.

Federer is not a direct entrant into an event he has won seven times and would need a wild card to enter, with tournament organisers expecting an official decision over his involvement "in the near future".

But while confirming his next scheduled appearances on court, Federer has included dates which occur after the Dubai tournament has concluded – a reason to believe he may skip the trip, like last he did in 2016.

Among the appearances which have been confirmed is the Match for Africa on 5 March against Jack Sock in San Jose, where Microsoft co-founder Bill Gates is also expected to attend an event that raises money for the Swiss number one's own foundation.

The right-hander has also confirmed he will return to defend his title at the BNP Paribas Open in Indian Wells, having scooped the crown in 2017 with victory over fellow countryman Stan Wawrinka.

Both dates had previously been announced but have now appeared on Federer's official website ahead of any announcement regarding an appearance in Dubai.

If Federer does indeed wish to compete in Dubai then he must accept a wild card offer by 12pm EDT on Friday 16 February in the US to be considered, so the decision could feasibly be delayed by at least another week.

Speaking after winning a seventh Australian Open in Melbourne, Federer was coy over his future plans which could also see him skip the clay court season again to assist his preparations to defend his Wimbledon title.

"It's possible I'll play [in Dubai] but it's also possible that maybe I just don't play anything," he said, according to The Evening Standard. "It depends on how the next week or so goes. Then I'll make a decision."

But that decision is yet to be forthcoming, one which will be eagerly anticipated by Nadal whose continued presence as world number one rests on Federer's participation.

The Spaniard's withdrawal from his Australian Open quarter-final to eventual runner-up Marin Cilic and Federer's subsequent retention of his title saw Nadal's lead at the summit of the ATP rankings cut to 155 points.

Despite Nadal pulling out five sets into his clash with Cilic complaining of a hip problem, the 31-year-old is expected to compete at the Mexican Open in Acapulco – where he has 300 points to defend as last year's beaten finalist – the same week as the event in Dubai.

But should Federer play in Dubai – he has never played at the Mexican event since its inception in 1993 – then Nadal would be powerless to prevent him reaching world number one if he wins the tournament.

Federer was knocked out in the second round in Dubai last year by Russian Evgeny Donskoy and thus only has 45 points to defend, meaning success in the ATP event – which is worth 500 points to the victor – will take him above Nadal regardless of his result in Mexico.

Roger Federer
Federer lost in the Dubai second round last year but his return is far from certain. Getty Images