Renault and Mercedes trail top three - Marko

Helmut Marko has backed paddock sentiment that Red Bull and Ferrari are heading into the 2011 season as the early favourites for the title.

"Red Bull and Ferrari are at eye-level," the energy drink-owned team’s driver consultant told Austrian newspaper Kleine Zeitung.

"And McLaren has the potential to catch up before the start of the season," added Marko.

Another potential frontrunner is Renault, after Robert Kubica and then his replacement Nick Heidfeld so impressed at recent Spanish tests.

"Renault are showing they are a lot more competitive than they were last year," Fernando Alonso said in a television interview, according to La Gazzetta dello Sport.

German Heidfeld, however, is not quite as confident.

"My guess is that there are still some teams ahead of us - especially Red Bull," he is quoted by F1’s official website on Wednesday.

Red Bull’s Marko agrees: "Mercedes and Renault are not quite at the level of the top three."