Fernando Alonso has reportedly named the two drivers who he thinks will be his biggest challengers for the F1 title through the remainder of the season.

Alonso holds a 40 point lead with the season now in its summer break, with Mark Webber the closest driver in the title race, with Sebastian Vettel, Lewis Hamilton and Kimi Raikkonen all close behind the Australia.

Given the way the first half of the season went, many believe that the title is still wide open heading into the Belgian Grand Prix at Spa at the start of September but Alonso said there were two of the chasing pack who he expected to emerge as the biggest threats.

"Hamilton and Vettel are the drivers we have focused on since the beginning," the Spaniard was quoted as telling Totalrace. "They are the biggest challengers, but all of the teams are close.

"Hopefully, they will fight among themselves and not one of them will dominate."

However, despite backing Hamilton and Vettel, Ferrari ace Alonso insisted that the title race was still all to play for.

"I think the distance between the top five, top six is not impossible to recover," he said. "You just need one good race or two good races and you are up there."