Roger Federer
Roger Federer (L) lost to Juan Martin del Potro in the finals of the BNP Paribas Open. In this picture, Argentina’s Del Potro shakes hands with Federer at the trophy presentation after a three-set victory in the ATP final during the BNP Paribas Open at the Indian Wells Tennis Garden, California, March 18, 2018. Harry How/Getty Images

Roger Federer’s first target entering the BNP Paribas Open in Indian Wells was to retain his world number one ranking, which he achieved by making the semi-finals with a straight sets victory over Hyeon Chung.

The second was to retain the title he won in 2017 in the Californian desert and become the first six-time winner of the Indian Wells Masters. He was unable to repeat the feat as he was beaten by Juan Martin del Potro in the finals Sunday.

The Swiss ace was favorite to win the title going into the summit clash, but failed to convert three match points as the Argentine fought back to end Federer’s unbeaten start to the season. The 36-year-old was 17-0 in 2018 — his best ever start to a season — and was seeking his third title of the year having won the Australian Open and the Rotterdam Open.

Despite the defeat in the finals, Federer is guaranteed to remain the world number one going into the Miami Open, which begins Wednesday. And, he is likely to remain the top ranked men’s singles player when the tournament in Florida ends owing to world number two Rafael Nadal’s absence.

The Spaniard is currently sidelined with a hip injury and is unlikely to return until the start of the clay court swing of the season at the Monte Carlo Masters in April. Nadal lost in the finals in Miami last year and hence will lose 600 ATP points by choosing to skip the tournament in 2018.

Federer is 290-points ahead going into the tournament in Miami, but his long-time rival’s absence ensures he has a buffer of 890-points as he plays at the second North American Masters Series event. The Swiss ace is defending the title and in turn 1000-points, and thus unless he loses prior to the quarter-finals he will remain the ATP men’s singles world number one until the end of the month.

However, a loss in the first four rounds of the tournament will see Federer drop behind Nadal in the standings despite the Spaniard not playing a single competition since withdrawing due to a hip injury in the quarter-finals of the 2018 Australian Open.

The top ranked duo are not under threat from any other player at the moment with world number three Marin Cilic 4755-points behind the Swiss maestro. However, former British number one female tennis player Annabel Croft believes Juan Martin del Potro could be in contention for the top ranking come the latter stages of the season.

The Argentine made three finals thus far this season and won two titles – the Mexico Open and the BNP Paribas Open. He is currently ranked number six, a far cry from two years ago when he was ranked number 366 in the world.

Del Potro was touted to be among the next generation of players that broke the Federer-Nadal stronghold when he emerged in 2009 to defeat the duo and win his first and only Grand Slam title at the US Open. However, a spate of wrist injuries saw him struggle to play consistently and thus was unable to challenge for major honors until recently.

"I don't think Roger is ready to give up his time at the top of the game just yet, but I do think he is definitely, definitely putting himself in the mix," Croft told Sky Sports. "Because of this rivalry that he does have with Roger Federer, and it's been denied for several years because of the injury problems that he's had, he is one of the few players who can mentally challenge the very best in the world.”

"It's taken him so long to get back into the situation because when you come back from injury you're going to be ranked a little bit lower you're going to meet these top players earlier in events and he's had to battle his way through all of that."