Seasoned Springbok wing Chester Williams was on Monday drafted into the national Sevens squad as replacement for Joost van der Westhuizen, who had to withdraw due to a shoulder injury.

After two days of national trials last week, Van der Westhuizen was appointed captain of the side, but the injury put paid to his plans of leading the national side in the World Cup Sevens tournament in Mar del Plata in Argentina later this month.

Natal Sharks loose forward Warren Britz was handed the captaincy.

Van der Westhuizen is the second experienced Springbok to withdraw from Norman Mbiko's squad. Last week battle-hardened Andre Venter also pulled out because of injury and his place was taken by the promising Eastern Province player Wayne van Heerden.

"I hurt my shoulder in the trials, but thought it would come right," Van der Westhuizen told The Mercury. "I pinched the nerve and there was bleeding as well. It means I can't tackle, and the doctors have said I need to rest for two to three weeks."

Mbiko said Van der Westhuizen's withdrawl would be a huge loss to the team, but was confident Williams could do the job.

"It's a big loss and he is hard to replace, especially at such a late stage. But there is nothing we can do. We still have a very good team and are confident of doing well."

According to Blue Bulls' doctor Henry Kelbrick, Van der Westhuizen needs at least three weeks' rest.

Williams' inclusion will by no means weaken the Sevens side. He is a skilful player whose omission from the original squad was regarded as a surprise by followers of the game.

The Lions winger's experience in the abbreviated version of the game should stand the South Africans in good stead and as one of the more skilful players in the country, his late inclusion could yet be a blessing in disguise.