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Mario Andretti believes Fernando Alonso is "keeping Ferrari alive" this season while team-mate Kimi Raikkonen has "work to do".

Ferrari has made a disappointing start to the new turbo era, with its engine down on power and its car lacking pace compared to its rivals. Despite the issues the team has faced, Alonso is still fourth in the drivers' championship and has scored 115 of Ferrari's 142 points.

Asked about Raikkonen's struggles this year, 1978 world champion and ex-Ferrari driver Andretti said the Finn had been eclipsed by his team-mate.

"Obviously he's moved away from Lotus, where I think it worked quite well for him, and gone back to Ferrari where he thought things would be peachy," Andretti told Formula One's official website. "But the fact that Ferrari struggled to begin with and that he's 'come in from the cold', so to speak, means he's having a tougher time than Fernando for sure. Fernando is one of those brilliant talents who will maximise everything you throw at him. He's keeping Ferrari alive very well. Kimi has a little bit of work to do I think."

Four-time and reigning world champion Sebastian Vettel has also struggled this year, but Andretti believes the Red Bull driver will return to form soon.

"Sebastian would probably admit himself that he's had a tough time adjusting to this big change. He was so tuned in with more downforce and all that. He's missing that considerably and up to now it has shown. But I think it's getting better and I have no doubt that he will totally embrace it because his talent is enormous. But it's probably taken more time than he thought it would.

"He's a champion and that will show eventually, but I'm sure no one is more disappointed than he is at this point. He's totally dedicated - he's one driver that I think is totally focused on his job; he has no other distractions and that's all he cares about. He'll get it done, I'm betting on that for sure. But I'm sure he's frustrated at the moment."

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