Although the grid for tomorrow's Japanese Grand Prix has yet to be decided, Lewis Hamilton already knows that he will forfeit five places after his team opted to change his gearbox.

The 2008 world champion is already struggling, having crashed out of the two previous races, only had fifty-three minutes of running yesterday after crashing during the opening practice session.

Today, like his rivals, he was restricted to a couple of installation laps when continuous heavy rain compromised running in the morning practice session and saw qualifying abandoned.

"In P3 today, we noticed abnormal gearbox oil pressure on Lewis's car, which we believed we had corrected ahead of this afternoon's qualifying session," said a McLaren spokesperson. "This afternoon, as we fired up Lewis's car several times in preparation for qualifying, we became aware that the symptoms were worse than we'd originally diagnosed, and a decision was later taken to change the gearbox ahead of tomorrow's qualifying session and the grand prix. As a result, Lewis will receive a five-place grid penalty for tomorrow's race."

The Englishman, one of five drivers still in with a mathematical chance of winning the 2010 title, is currently twenty points behind championship leader Mark Webber.