Ferrari believe Rubens Barrichello can still give team mate Michael Schumacher a hard time this season despite the Formula One champion's perfect start.

Technical director Ross Brawn told reporters at the Spanish Grand Prix on Friday that Schumacher's dominance, with four victories in four races, had unsettled the Brazilian but he would fight back.

"I think it's probably the toughest job in Formula One to be driving as a team mate of Michael Schumacher," said Brawn.

"It's such a tough job that you have your setbacks...Rubens won the last race of last year and I think he came into this season very confident that he could have a chance of beating Michael.

"And Michael started this year in unbelievable form and it was just a bit of a knock for Rubens," he said.

"I think he's come back now. He had a reasonable test last week. He looks in good shape here."

While six times champion Schumacher is on course to equal Nigel Mansell's record start to a season at the Circuit de Catalunya on Sunday, Barrichello has been pushed off the podium in two of the four races.

At the last San Marino Grand Prix he qualified fourth and finished sixth. But the Brazilian was quicker than Schumacher in Friday's second practice session.

"There's always a chance, and it's not necessarily the case with Rubens, that when you're up against someone like Michael and trying to beat him that you can overstretch yourself," said Brawn.

"You can try and do too much and you go down the other side of the slope. Rubens is trying to keep that balance but he really does have the toughest job in Formula One because he's in the same equipment against the strongest driver that there's been in a very long time."

Brawn said that Ferrari remained happy with a driver who has a contract with the team to the end of 2006.

"Rubens is a great team member and he's had some fantastic races for us," he said. "We realise the challenge he faces.

"I think he's been a bit disappointed this year as well because I'm sure he thought he could give Michael an even harder time and I'm sure on occasions he will. But it's been a bit of a quiet start to his season."