Lewis Hamilton will sign his new contract with Mercedes this week at a time when Ferrari have given him food for thought a third Formula One world title may not be such a formality after all.

The negotiations, conducted by Hamilton himself with the top brass at Mercedes, notably motorsport boss Toto Wolff, is all done and dusted, with the paperwork now in the hands of the lawyers to sign off.

"It should be done this week," said Hamilton.

"There is no reason why it shouldn't be. Honestly, it's 99.6 per cent done. There's no negotiating left, it's just legal stuff."

There was one cheeky question in Hamilton's post-Malaysian Grand Prix debrief as to whether Ferrari's win in Malaysia had made him think of potentially switching sides. Hamilton smiled before replying: "No, don't be silly."

But Sebastian Vettel's victory, just a fortnight after a Mercedes one-two in Australia had suggested 2015 would be as easy for the Brackley-based marque as 2014, totally blind-sided Hamilton.

"I didn't see it coming," added Hamilton, forced to settle for second behind Vettel, with Mercedes team-mate Nico Rosberg third.

"I went into the race very open minded in that I knew things would be tougher, but even so I went in with a good feeling we would be able to fight and win the race. In the end it was damage limitation. If that was a bad day, where we still get second and third, then that's pretty good."

Hamilton, though, appreciates he now has a battle on his hands if he is to win that third championship, and not just with Rosberg.

"I don't think the win was a one-off. I don't think they (Ferrari) were lucky or it was a fluke. They just did a solid job," assessed Hamilton.

"But nor do I think it was a wake-up call for us. I don't think we were in need of one, after all we won by 30 seconds in the last race. But regardless of whether you're winning everyone can always do with...not a kick, like a pinch.

"It has given us a pinch to suggest, 'Oh, okay, we've got a race on our hands'.

"We're a racing team, and we will be quicker in the next race. We'll manage, we'll be absolutely fine. We've a great group of people, a great approach, and from this we'll take a step back.

"They (Ferrari) are too close to us in the championship so we'll work very hard to analyse what we learned and apply it so it doesn't happen again at the next race."

Hamilton was at least gracious to recognise the return of Ferrari and Vettel was "good for the sport" as the overwhelming dominance of one team can look bad.

Moreover, Hamilton was left offering a penny for the thoughts of one man who must be feeling sick to his stomach - Fernando Alonso.

The Spaniard quit Ferrari at the end of last year - with Vettel his replacement - after growing tired of waiting for his own third world title, believing a return to McLaren would further his cause.

So far, McLaren's renewal of their partnership with Honda has been a disaster, although all within the team claim the long-term future is bright.

"It's nice to see Ferrari back up there," insisted Hamilton. "But I was sat next to Sebastian (in the post-race press conference) and I thought to myself, 'What is Fernando thinking?'.

"I remember when I left McLaren and joined Mercedes, we were better the next year. I had a good feeling then.

"But he's almost done the opposite of what I did. It could have been him (winning) today! It's just strange how things turn out."