Patrick Head has admitted that Kazuki Nakajima 'needs more speed' if he is to retain his Formula 1 seat at Williams into the 2010 campaign - with the Japanese ace having failed to trouble the scorers at all so far this year, whilst team-mate Nico Rosberg has notched up no fewer than 30.5 points.

If paddock whispers are to be believed, then Williams will dispense with its Toyota engine supply at the end of the current season - and therefore, most surmise, also with Nakajima's services, given that the 24-year-old came as part-and-parcel of the agreement with the big-budget car manufacturer in the first place, initially as a test driver and subsequently a race driver from the final grand prix of 2007 onwards.

However, during that 32-race stint, the son of 1980s F1 star Satoru Nakajima has succeeded in scoring on only four occasions and totalling just nine points to Rosberg's 52.5 over the same period. With a number of drivers on the market, it seems the Aichi native's days at Grove could be numbered - and Head does little to dispel that suspicion.

"Unfortunately, although Kazuki has very much improved - I think he's got into the top ten in qualifying two or three times this year - none of his races have really worked out that well for him," acknowledged the multiple world championship-winning outfit's respected co-founder and engineering director, speaking exclusively to Radio. "He needs just a little more speed to get some good results. He needs to move up a couple more places on the grid really."

Head was less willing to comment upon fevered speculation that Williams could indeed be fielding an all-changed driver line-up next year, with the highly-rated Rosberg hotly-tipped to jump ship to McLaren-Mercedes alongside Lewis Hamilton - "I'll leave it to the rumour mill," he insisted. "All these things are in discussion" - but he was open regarding his views on the Oxfordshire concern's performance to-date in 2009.

With ten points finishes from 13 starts - all courtesy of Rosberg, with highlights of fourth places in both Germany and Hungary - the team currently sits sixth in the constructors' title chase, eight markers adrift of the works Toyota operation in fifth. Though last weekend's Italian Grand Prix at Monza witnessed a failure to score for the first time in nine outings, Head is confident of getting back on-track again next time out in Singapore - particularly if Nakajima can finally break his 2009 points duck.

"When we go to Singapore I hope we can be stronger," mused the 64-year-old Englishman. "We missed out on getting points early in the season, mainly through operational problems. We had no reason not to be able to get points - the car was reliable - but we just didn't make a good job of some of the wet/dry races earlier in the year.

"It's respectable, but it's no cigar - it's nothing special. We're sixth in the constructors' championship; maybe there's a chance we could get to fifth, but that's really not where we want to be."