Ferrari's Eddie Irvine has vowed to maintain his lead of the Formula One world championship at this weekend's Brazilian Grand Prix at Interlagos, despite the insistence of the team's sporting director, Jean Todt, that team orders, which restrict Irvine to running interference to team-mate Michael Schumacher, have not changed.

Irvine scored a memorable first grand prix victory in Melbourne last month and is hoping to replicate the performance in Sao Paulo this weekend. "I want to leave Interlagos, at the minimum, leading the world championship," the Ulsterman said yesterday. "To score a few points, that should be relatively easy. I want to go to Imola leading the world championship. I want to lead it for as long as I can. If I can lead it at the end, then fantastic. But that's a long way off at the moment."

However, despite rumours after the Australian Grand Prix that Irvine was finally to be let off the leash which sees him play perpetual second fiddle to Schumacher, Todt would not be drawn on whether team orders would change if Irvine wins in Brazil.

"We are not in a situation were one driver is 10 points ahead of the other going into the last race of the championship," he said flatly.

"Eddie did a great job (in Australia), but everybody has been saying that Ferrari has been totally depending on Michael Schumacher, but this was a good answer because it proved we are depending on two drivers, which is what we wanted to achieve. Let's wait until the finish of the Brazilian Grand Prix and see what happens."

Change has been on the agenda at Jordan, with designer Mike Gascoyne saying that a new engine set-up will be tried at Interlagos, along with several aerodynamic changes which it is hoped will spell "a significant step forward since Melbourne".

"There has been a change in the way Jordan is competing at the start of this season compared with 1998," he said. "We are no longer simply trouble-shooting and fixing problems just to finish a race. Instead we're instigating changes to make the car even more competitive, as, realistically, there is a still a large gap to close if we are to catch the top teams."

Team owner Eddie Jordan remained, as ever, optimistic about the team's progress and chances for the Brazilian race.

"Everyone at Jordan has been pulling together after a fantastic start to the season. The competition beneath McLaren and Ferrari remains tough, but I think we are proving to have a reliable package, and our performance and improvements in testing over the past weeks have been strong."