Christian Horner says that next week's test in Bahrain is 'important' for reigning champions Red Bull.

Red Bull completed just 21 laps in the RB10 at the first test at Jerez due to issues with the cooling on its car, a situation which was exacerbated by Renault's problems with the new power unit.

"Well obviously there's quite a bit to do but there's still a fair bit of time before the first race and the Bahrain test next week is an important test so obviously everyone is working very hard at Renault and in Milton Keynes," Horner told Sky Sports News.

"We don't want another week like Jerez but that's what testing is for; you sort your problems out in testing so as not to have them at the race."

Horner also insisted that Adrian Newey was not to blame for Red Bull's problems.

"No, no," he said when asked whether Newey's notoriously tight packaging was their key weakness.

"I think there are a few things that we needed to tidy up on our side but nothing major. Obviously Renault have got some issues that they are tidying up as well but these cars are so complicated that little problems can cause big failures."

Renault's other customers, Toro Rosso and Caterham, also encountered problems at Jerez, with the Italian team managing 54 laps, on top of Caterham's 76.

Renault trialled upgrades to their power unit on Lotus's E22 at Jerez last weekend.

Lotus conducted a filming day on Saturday at the Spanish circuit and ran the full 100km permitted under the regulations, without any major problems.

Lotus's running at Jerez has given Renault renewed hope that upgrades to the power unit will allow all four of their teams to put in a reliable and competitive showing in Bahrain next week.