The German withdrew from the Australian Grand Prix after Friday practice, feeling he was not fit enough to race after hurting his back in a crash at the Race of Champions in January.

He went on to miss the Chinese Grand Prix as well before making his return to action in Bahrain.

But Wehrlein said that given the severity of his injury, his team expected him to miss the first four races of the season.

"The team thought that my first race would be Barcelona," Wehrlein told Motorsport.com. "For me there was no point. I couldn't believe that I would skip four races, so I said: earlier than Barcelona."

Wehrlein was assisted by experienced driver physiotherapist Josef Leberer during his recovery, and the Sauber racer reckons that without his support he would not have been able to come back before Spain.

"To work with Josef, someone with so much experience, who is so successful in this sport and so many titles and working together with many, many great drivers is, of course, good for me because I learn a lot from his experience," he said.

"When he told me things like that Barcelona should be my first race, for me this was a big motivation to say: 'No, it's not Barcelona, it's before Barcelona.'

"And then to prove them also right that I'm doing everything, I'm pushing very hard to come back earlier than this, this was a big motivation for me.

"Of course he helped me everywhere he could with all his experience. I think without all the support I was getting I probably wouldn't be back now still."

The Sauber driver, who scored his best F1 result to date in Barcelona thanks to an eighth-place finish, says he is now feeling fully fit.

When asked if he thought he was still at a disadvantage compared to his rivals, he said: "No. Of course I did fewer races, less time in the car than everyone else but that's just the past now.

"I'm focusing every race on the maximum I can do, the maximum performance. I'm feeling quite happy in the car and the team. That's all good."

Interview by Oleg Karpov and Filip Cleeren