Don't write Nadal off the No.1 spot, says Gilbert

London: For Rafael Nadal to bridge a 7,000-point gap with Novak Djokovic in the ATP rankings looks like a tall order, even for a player of his qualities, yet he could still threaten the Serb's hopes of ending 2013 as world No.1. With the French Open looming large on the horizon, Nadal is back in the claycourt groove as he continues his comeback from a knee injury that sidelined him for seven months.

The Spaniard has won four titles in six tournaments since returning in Chile in February, finishing runner-up in the other two, yet remains in unfamiliar territory outside the world's top four. Starting in Madrid next week, however, where he suffered a surprise third-round exit last year to compatriot Fernando Verdasco, fifth-ranked Nadal can start making inroads.

While the Mallorcan must defend 3,000 points at the Rome Masters and then at Roland Garros, where he will be chasing an eighth French Open title, the second half of the year looks like being a win-win situation for the 11-times grand slam champion.

A stunning second-round defeat by Czech Lukas Rosol at Wimbledon last year proved to be his final match of 2012, meaning the Spaniard will have six months to harvest ranking points and close the gap on those above him.

Djokovic is hoping to finish a third successive season as world No.1 but Brad Gilbert, former world number four and coach to Andre Agassi, believes Nadal has will be breathing down the Serb's neck later this year.

"To me this is the meatiest part of the season," Gilbert told ATPWorldTour.com

"You've got two Masters 1000s back-to-back and then the French and Wimbledon. That's 6,000 points up for grabs over a short stretch, and what happens during this time will set the tone as to who has a shot of finishing No. 1.

"Djokovic is in good position now but it still could be a very tight race."

Djokovic, world number two Roger Federer and number three Andy Murray will all be defending sackloads of points after the French Open, and providing Nadal suffers no injury setbacks he will be relishing a pressure-free second half of the year.

Gilbert said Nadal's decision to delay his comeback until after the Australian Open and then skip the Miami Masters was paying dividends.

"What a tremendous effort to be in the final every week he's played. I love the way he goes about his business," Gilbert said. "He didn't rush back until he was close to 100 percent, and the results back up that he made the right decision."