Sebastian Vettel admits the running Red Bull managed to achieve during Friday practice for the Australian Grand Prix was "a big relief".

After a tough pre-season of testing during which Red Bull had numerous reliability problems - including a day at the final test where Vettel failed to complete a lap - Friday at Melbourne saw both cars setting times inside the top 10. Vettel alone completed 51 laps across the two sessions and set the fourth fastest time in FP2, and admitted afterwards that the day had panned out better than expected.

"It was very good, obviously, and a big relief," Vettel said. "A lot of work went in to this. I think the biggest difference is that we got new parts; not necessarily performance parts but new parts. We didn't have the spares for testing and ended up with a fix here or there so I think that's the biggest difference.

"Neither of us had big problems today, the cars were running and the balance felt very good. In terms of speed obviously we know that there is still a lot to come but so far it feels very good."

And Vettel also said he had gained more confidence in the RB10 after relatively trouble-free running, but isn't getting carried away by the progress made.

"I think every lap right now is useful. Obviously I've done a lot of laps in my life but not so much in this car and in these conditions. It's a lot of new stuff for the whole team, for myself and step-by-step we have to take each step and make sure we don't rush anything. Today was a very good day and let's build on that."