McLaren team principal Martin Whitmarsh has admitted that he is 'concerned' by the car's performance in the second practice session ahead of the Australian Grand Prix.
Jenson Button was 2.386 seconds off the pace, while Red Bull's Sebastian Vettel managed to secure the quickest times in both sessions.
"It was one of the hardest days I can recall," BBC Sport quotes Whitmarsh as saying. "We were lacking overall grip. We had understeer, poor ride. So a very difficult day, one where we didn't go forward during the day, so that's a bit of a concern."
Button, who finished in 11th place during the second practice, won the Grand Prix in Melbourne last season.
