Mercedes boss Wolff says Vettel's Malaysian GP win a 'wake-up call'

Hot temperatures hampered Mercedes' form at Sepang, where track temperatures peaked at 62C, while Ferrari was able to manage its tyres well.

As a result, Vettel beat Lewis Hamilton and Nico Rosberg on outright pace, securing Ferrari's first win since the 2013 Spanish Grand Prix and confirming its status a key rival for Mercedes this season.

It ended a run of eight straight grand prix wins, which stretches back to last year's Italian Grand Prix.

Wolff admits that he was surprised by how quickly Ferrari appear to have closed the gap.

"We didn't expect it to happen at that pace," said Wolff. "We were pretty dominant in Melbourne.

"We were always a bit sceptical about our own advantage and believed we had to keep sharp and keep developing in order not to be caught up.

"In two weeks you are caught up and you lose the race fair and square on track which is a bit of a wake-up call, which is good for us."

Looking ahead to the remaining 17 races, Wolff said the team will explore all options in a bid to hold off Ferrari.

"I think they have done a great job, they have a good car, good engines, great drivers and we just need to analyse in the next couple of days what went wrong," he said.

"Do we need to improve? Do we need bring developments forward? What are we doing with engine number two?

"We need to increase the pace of our development."