Welsh try-scoring machine Shane Williams has gone seven games on tour with the British and Irish Lions without once crossing the whitewash.

But the diminutive Ospreys wing, with a national record 46 tries in 65 games for Wales and six in nine Lions games, is targeting a try or two come the third and final Test against the Springboks in Johannesburg on Saturday.

Williams' early indifferent form on tour saw him lose out to England's Ugo Monye for selection for the Lions' first Test match against the Boks, which the hosts held on to win 26-21.

He then came on as a replacement in the second Test, which the Boks won 28-25 thanks to a Morne Steyn penalty kick on the stroke of full-time.

But the IRB player of the year in 2008 has been handed a starting spot for Saturday and is relishing the chance.

"I was disappointed not to have started the first two Tests," admitted the 32-year-old.

"I've been beating myself up about how I've been playing although I never assumed I'd come over here and walk straight into a Test berth.

"I want to go out there and win a game we deserve to win," said Williams, who did not feature in the third Test against New Zealand four years ago which the All Blacks won 38-19 to seal a 3-0 series win.

"There's no danger of a whitewash - we're up for this game," he stressed.

"South Africa have made a lot of changes. They might not be as structured as in the first two games. We have worked hard to try to play to the same patterns.

"I've got my chance this Saturday when I start the Test. I'm thrilled. There's a lot relying on this game personally and for the team.

"I've trained as hard as possible. It was nice to be on the bench last week and now to be starting is great."

Williams has admitted that he has at times felt burdened by the title of the world's best player in a season during which he has patently failed to fire on all cylinders.

"However, I'll go out there fully confident, and hopefully enjoy myself and express myself," he said.

"I've been lucky over the years in that I've been quite a prolific scorer. But you do hit dry spots, I mean look at Premiership strikers, they're not always scoring goals.

"I try not to dwell on it. The tries will come provided you work hard, enjoy yourself and get involved in all areas around the park.

"If I play well I'm sure I'll score a try," said the wing who scored two memorable tries in successive matches against the Springboks in Pretoria and Bloemfontein during Wales' summer 2008 tour.

An added incentive for Williams is that the game will most probably be his last in Lions colours.

"It's my last opportunity: I won't be wearing the Lions shirt in four years' time," he said.

"It's a Test we want to win. It's 2-0 in the series but we've been a bit unlucky. We're from four proud nations and we want to go out there and play as well if not better than the last two weeks to win the game."

Williams acknowledged that a childhood steeped in Welsh rugby folklore made the Lions all that more special.

"The British and Irish Lions are massive in Wales. Being Welsh, you grow up watching and hearing about all the legends of the 1970s.

"Certainly playing for the Lions is the pinnacle and I've had the privilege to have done it on two tours," said Williams, whose schoolboy sporting activities were concentrated more on gymnastics than rugby.