Toto Wolff has admitted Mercedes is having to push its limits to keep Ferrari at bay, which he admits could go some way to explaining its recent reliability concerns.

Lewis Hamilton will start the Chinese Grand Prix from the back of the grid after suffering an ERS problem in qualifying before setting a time.

It comes after a pre-event gearbox change would have forced him to start five positions lower than he would have normally qualified, only for the ongoing technical issues - which have forced Mercedes to change his entire power unit - to leave him at the back anyway.

Though relaxed about the technical problems as a whole, Mercedes F1 boss Wolff does hint that the team is having to push the W07 to the limit in order to resist the challenge of Ferrari.

"If you push your performance limits like we have to do now for Ferrari, you're always going to try to push the limits. This is a mechanical sport and reliability is key to our set up and we have a well functioning structure but it is motor racing and things like this can happen."

Hamilton himself, however, is more relaxed about the problems, saying he doesn't believe the looming Ferrari threat is pushing Mercedes to the 'edge'.

"I don't think we're on the edge more than we ever have been, so I don't believe that it's because we're battling with Ferrari. It's just one of those things. I can't really remember what happened with the gearbox, I think that's just a new unheard of thing that we've had. But it's good to discover these things so we can do analysis and try and make sure that it doesn't happen again."