Sebastian Vettel accepts he has to be better after a testing start to the Formula One season.

Ferrari were surprisingly off the pace at the opening race of the season in Australia having impressed in pre-season testing.

Vettel's new team-mate Charles Leclerc improved noticeably in Bahrain and was on course for victory until an engine problem saw him slip to third.

But it was another tricky outing for Vettel, who ambled to fifth after spinning on lap 38 when overtaken by eventual race winner Lewis Hamilton.

Ahead of this weekend's Chinese Grand Prix in Shanghai, Vettel was asked if Leclerc's strong showing had him "on the run", but the German instead believes it is more a case of him having to get the best out of the car.

"I don't know what you guys sometimes imagine on the other side," Vettel replied in quotes reported by F1's official website. 

"I haven't come across a driver that was a pain in the ass, and I hope I never will. I think prior to the season I said it's a different person so it was going to be a new and different challenge. 

"I have always shown respect when other people do well, as he [Leclerc] did in Bahrain.

"I wasn't happy with my performance, not happy with the feeling yet with the car, the feeling I had in testing and so on. I know that I can be better and I know that we have lots of races to show and prove that. But at least when I'm not at the top of it, it's good that he is.

"It was a surprise when we came to Australia and the car wasn't anywhere near what we had in Barcelona, with the car being very alive and unstable. 

"Bahrain I think the conditions were tricky and everyone was struggling with the wind and so on. We were surprised to find ourselves faster down the straights than other people, especially with Australia having been on the back foot. We'll see where we are here."

With Mercedes starting the season with a pair of one-two finishes, Valtteri Bottas and Hamilton exchanging wins, Vettel recognises the importance of a stronger showing in China, where he expects Red Bull to also impress.

"We need to get everything right [in China]. It's extremely tight at the top. I expect Red Bull to be closer here than they were in Bahrain – I'm not sure what happened there. 

"But I expect it to be very close."