Williams optimistic of significant progress in Japan

Gillan joined the team for the first time in Singapore to shadow departing technical chief Sam Michael, who announced his decision to leave Williams earlier this season and will become McLaren's sporting director in 2012.

Williams has had a tough season so far, with drivers Rubens Barrichello and Pastor Maldonado invariably qualifying and finishing just outside the top 10.

Driveability issues have been cited as one of Williams's major issues in 2011, but Gillan said real progress had been made in understanding the problems since the last race.

"Our levels of understanding regarding the driveability issues of the FW33 have increased significantly since Singapore and we are currently working hard to optimise the set-up and improve the car going into the Japanese GP," he said.

"We obviously need to ensure that the car operates in the optimal aerodynamic window - this is fundamental to maximising our performance and we aim to be fighting for a points finish with both cars."

Williams has only taken three points finishes so far this year and has yet to finish a race higher than ninth.

At present, it is ninth in the constructors' championship, 24 points adrift of nearest rival Toro Rosso.