Valtteri Bottas will take confidence going into the season opening Australian Grand Prix in two weeks knowing his Williams has the pace and reliability to be a force.

Bottas topped the times on the final day at the Catalunya circuit clocking 1:23.063s on the 33rd of his 89 laps.

Ferrari recruit Sebastian Vettel was next in 1:23.469s ahead of Felipe Nasr’s Sauber (1:24.023s).

The FW37 Williams-Mercedes continued its promising pre-season form with Bottas focussing on performance and aero work.

“One of the main points we have learnt is that the FW37 is very reliable,” Bottas said.

“The car we are taking to Melbourne is very competitive and should make for an interesting start to the season.”

Daniel Ricciardo was set the fourth fastest time in the Red Bull, registering a 1:24.638s ahead of Sergio Perez (1:25.113s) in the Force India.

Nico Rosberg was fifth with his Mercedes setting a best tour of 1:25.186s with the the champion team spending the final day targetting set-up evaluations.

Mercedes amassed a total of 378 laps or 2066km at the Barcelona circuit over the four days of testing.

See below times on Day 4 at Barcelona