Ricciardo: Engine performance Red Bull F1 team's only question mark

After a torrid, winless season dominated by rows over future engine supply, Red Bull is sticking with Renault power under TAG Heuer badging.

Though Ricciardo admitted Red Bull's chassis was also below par early in 2015, he now feels only the engine will prevent a title challenge.

"I'm not going to go in thinking we can win the title. That would be the wrong thing to do," he told Autosport.

"If it works, awesome. I think we've got the platform.

"The way the team developed the car last year, it's really proven not only the quality of people, but the motivation and the hunger still within the team.

"That's been the most promising thing: I haven't seen any doubters or anybody lose motivation. Everyone's still as hungry as ever.

"Unfortunately now it's probably always going to be dependent on which engine we have and that's going to dictate the success a little bit.

"But mechanically we can definitely build a good car for 2016.

"How good is the engine going to be? That's the question."

Having won the first three grands prix of his career in 2014, Ricciardo set a target of matching that last term, but quickly realised that was unlikely.

"Speaking of expectations, we really met none of them, that's reality," said the Australian

"Winning three races in 2014, I came into last year thinking 'OK I'll win at least three'. It's only natural.

"Renault had one year of development, we'd had a winter of testing, we'd come out swinging. So sure I had expectations.

"After the first few races I had to throw all that out of the window and reset.

"But in saying that I think we've turned it around a lot.

"Even though we struggled with the engine, I felt the chassis wasn't there at the first few races."