“It would top it all off,” said the 88 times-capped Cardiff Blues flanker, who has embarked on a third Lions tour following Australia in 2001 and New Zealand four years ago.

Despite Williams’ world-class ability, though, he has yet to start a Test match for the Lions.

His one taste of it came as a replacement during the 38-19 third Test defeat against New Zealand in Auckland, which is scant reward for a player with such talent.

But Williams is ready to make his mark, whether he lines up against the Springboks next month or not.

“Ideally, you would be starting in the Test side and winning the series, but if you don’t start, there is still a very important role to play,” he added.

“Geech (Lions head coach Ian McGeechan) made that point earlier this week. He said one of the greatest Lions he ever worked with was Jason Leonard in South Africa 12 years ago.

“Jason didn’t start, but what he did behind the scenes for the other boys to make sure they won the series was outstanding.”