Sebastian Vettel has conceded that Mercedes are a "long way" ahead of Red Bull following the first two practice sessions for this weekend's Bahrain Grand Prix.

The defending world champion was seventh in the second session and teammate Daniel Ricciardo posted the fourth fastest time, while Mercedes's Lewis Hamilton led the field.

The German told Sky Sports News: "For today, I think it was a good day, a stronger day for us. It's very difficult where we are in terms of pace but it's really easy to say that we're not with Mercedes.

"We had a strong day today, no issues with both of our cars nothing went wrong, a lot of things were learned. Now it's up to us to see some improvements tomorrow.

"They've proven again today that they're quite quick so it will be a long way for us to catch up but in the long term it's important that we make bigger steps than them."

Qualifying for Sunday's race takes place tomorrow.