Johannesburg: Left-arm swing bowler Wayne Parnell and leg-spinner Imran Tahir have been added to South Africa's squad for the fourth Test against England.

After the agonising failure to claim England's final wicket in the third Test at Cape Town, South Africa travel to Johannesburg trailing 1-0 in the series, and so have chosen to cover all options at a venue where spin can be effective, but which also promises to assist the seamers after weeks of damp weather.

Parnell, 20, has been a regular for South Africa in limited-overs cricket and produced some memorable performances in the World Twenty20 in England in June. He was included in South Africa's squad for the first Test in Centurion only to be released from the squad on the eve of the match in favour of Friedel de Wet.

De Wet, however, has been struggling with a back injury that required an injection on the final day at Cape Town. He was noticeably down on pace throughout his last-day spell, and his place in the squad will depend on the outcome of a scan. Makhaya Ntini was another name in the frame for a last hurrah, but his latest omission has all but confirmed his international retirement.

Tahir, meanwhile, has been in the wickets for Easterns this season, and was also prolific for Hampshire in his recent stint in county cricket, claiming 52 wickets at 32.90. He played two matches for Pakistan A back in 2005, and has also featured for Middlesex and Yorkshire.

Alviro Petersen and Ryan McLaren, who have featured in the squad for all three Tests, have retained their places. "This is a must win Test for us," said South Africa's convenor of selectors, Mike Procter, "and we have covered all our bases as far as the composition of our attack is concerned."

Squad Graeme Smith (capt), Hashim Amla, Mark Boucher, AB de Villiers, Friedel de Wet, JP Duminy, Paul Harris, Jacques Kallis, Ryan McLaren, Morne Morkel, Wayne Parnell, Alviro Petersen, Ashwell Prince, Dale Steyn, Imran Tahir.