Former world champion Nico Rosberg believes Sebastian Vettel is struggling to enjoy life at Ferrari.

The four-time world champion heads into his home race at Hockenheim on Sunday already a staggering 100 points adrift of Lewis Hamilton in the standings.

It is approaching a year since Vettel, 32, last celebrated a win. His number one status at Ferrari is being challenged by young Charles Leclerc in the sister car. A fortnight ago at Silverstone, Vettel finished 16th after he crashed into the back of Red Bull's Max Verstappen, the latest in a long line of mistakes.

Ferrari's form in pre-season testing suggested Vettel would have the machinery to end the Italian team's 12-year championship drought. But so concerning is the German's form that there are question marks as to whether he will even see out his Scuderia contract which expires at the end of next season, jumping before he is pushed.

"Sebastian is having a rough season," Rosberg said.

"You start the year expecting to be the world champion and when things go wrong it is really tough. Being a Ferrari driver is the ultimate pressure. You have the whole of Italy on your back. It must be difficult to enjoy.

"F1 affects your mum, dad, and wife. That is why it is so intense. The suffering and the joy goes all the way to your home, and it never stops.

"Now, there is huge pressure from Leclerc, too, a young guy who is driving so well. Verstappen is in front of both Ferrari drivers in the championship. Can you believe that? S***.

"We know that Seb is one of the best out there if he drives the way he can. I hope he finds his way because that is what he needs right now."

Rosberg believes the pressure is weighing heavily on Vettel

There is little evidence, however, to suggest Vettel is set to turn a corner.

It was here a year ago, where Vettel, on course to win his home race and extend his championship lead over Hamilton to 20 points, skidded off the track and into the gravel. Hamilton won the race to land a 17-point cushion over his rival. Vettel has not returned to the summit of the standings since.

Indeed, in the ensuing 12 months since his Hockenheim horror show, the German has scored an eye-watering 170 points fewer than Hamilton, 36 fewer than Valtteri Bottas and eight short of Max Verstappen's tally - the Dutchman racing for the inferior Red Bull team.

His collision with Verstappen took his error count to seven in 21 appearances. Following his crash here, he spun in Monza, Japan and the US last year and in Bahrain at the start of this season, too. He then fell off the road while leading in Montreal.

Three of those errors came while in wheel-to-wheel combat with Hamilton. Has the British star, on course to beat his rival to a third successive title, got under Vettel's skin?

"You need to be careful of trying to pinpoint it to one single factor," said Hamilton's team boss Toto Wolff.

"Undoubtedly, Lewis has a great ability and talent, but I know Sebastian, and his record speaks for him. He has won four championships and that doesn't come from nowhere. I have no reason to believe that he will not recover."

Vettel, whose father Norbert is supporting him this weekend, will take some comfort from being fastest in first practice. Leclerc led the way in the afternoon running with Hamilton third.

"I always put myself under pressure so I can't be happy if things go wrong," said Vettel.

"The pressure I put on myself is bigger than any external factors. It doesn't feel like a burden driving for Ferrari. It is a privilege. My mission is to get back to winning ways."

Hamilton, 39 points clear in the race for the championship, is bidding to eclipse Michael Schumacher by winning the German race for a record fifth time.