Juan Martin del Potro and Kevin Anderson are the two players to challenge Roger Federer at Indian Wells this year, says Mark Petchey.
Federer will start as favourite on the hard courts of Indian Wells as he bids for a record sixth men's singles title in California, where neither Rafael Nadal nor Stan Wawrinka will feature because of injury.
But while Petchey says Federer is playing with nothing to lose, he believes Del Potro and Anderson have the game to take on the Swiss in the year's opening Masters 1000 Series event, live on Sky Sports Arena from Thursday.
"If Roger puts his best tennis out there, he is the best player," said Petchey. "He is playing with such utter freedom right now. He has got nothing to prove in terms of winning titles.
"This is all about his love of the sport which is clearly unconditional. He doesn't need to rewrite another chapter in terms of his legacy - that has been done in the last 15 months. He is not only winning slams, but is now back at world No 1.
"When he plays the way he has done recently it is a pretty tough combination for the other players on tour to face right now. For him, it is almost an irresistible situation. Just go out there and play with house money.
With Nadal and Wawrinka missing Indian Wells through injury, Petchey says Del Potro and Anderson are well set to stake their claim on the title, should Federer slip up.
"Del Potro has beaten Roger in the final of a major and is clearly playing with confidence," he said. "He is back in the top 10 which is always crucial when you are taking on somebody like Roger.
"The great thing about Del Potro right now is his backhand - because of all the wrist injuries that he has had. We have seen significant tactical changes in terms of hitting over it and also using the slice.
"His backhand now is arguably more versatile than it was when he won the US Open. It is probably helping him at this stage of his career to become a better player.
"Mentally, he has the belief that when he plays the big players he is capable of beating them. There are not many out there that have been allowed that particular strength. That is a crucial element."
On Anderson, he said: "Neville Godwin has done a fantastic job [prior to their parting of ways] with Kevin, who is an incredibly hard-working and determined character in terms of getting the most out of himself. He deserves a lot of the credit as does Neville in terms of how much he has improved as a player.
"His game, in terms of his volleying and willingness to come in, has been crucial in terms of him breaking into the top 10. Another underlying factor is confidence. Having a single digit next to his name is going to make him feel even more invincible against the majority of the tour.
"He has got a new coach in Brad Stine, who has done good work in the past and is trying to introduce a few new facets to his game.
"He has such a big game because he returns hard - on his bad days he doesn't make enough returns, but the majority of time you feel under pressure even when you are serving against him because he is taking such a big swing at the return that you don't get too much respite and rhythm.
"His serve is also one of the best out there. You have got to have something pretty special when you go out on court against Roger - otherwise you are not going to stand a chance and those two players right now certainly have enough in their game and confidence to take him on if they were to meet."
You can watch Indian Wells with coverage getting underway from 7pm on Sky Sports Action and via the red button on the same channel this Thursday. You can also watch it from 10.30pm on Sky Sports Main Event.
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