Johannesburg: Specialist opening batsman Stephen Cook has been added to the South African squad for the fourth and final Test against England starting in Centurion on Friday.

Cook, 33, tops the domestic four-day competition averages with 415 runs at an average of 83, including two centuries.

The son of former Test opener, Jimmy, he carried his bat for an unbeaten 53 for South Africa A when they were bowled out for 136 by England before the first Test.

He was also the leading run-scorer in last season’s domestic first-class competition with 889 runs at an average of 63.50.

There were widespread calls for Cook to be included at the start of the series, but the selectors opted to stay with Stiaan van Zyl, who had not been a regular opener before being handed the job for South Africa on tours of Bangladesh and India last year.

Van Zyl made only 69 runs in five innings in the first three Tests against England.

Captain AB de Villiers admitted after his side’s seven-wicket defeat in the third Test on Saturday that the lack of a specialist opener had been a weakness in the team.

Quinton de Kock, a late withdrawal from the third Test after suffering a knee injury the day before the game, will keep wicket. His replacement, Dane Vilas, drops out of the squad. Fast bowler Dale Steyn was again included in the squad although he continues to battle with a shoulder injury.

Meanwhile, England seamer Steven Finn appears likely to miss the fourth Test because of a side strain, team officials confirmed.

Finn felt tightness in his left side during England’s series-clinching victory at the Wanderers and was sent for scans on Sunday, the day after England’s dramatic seven-wicket win put the tourists 2-0 ahead with one test to play.

However, head coach Trevor Bayliss remains pessimistic about his chances of playing in the final test, paving the way for Chris Woakes, Chris Jordan or Mark Footitt to vie for a starting role at Centurion as England target an emphatic 3-0 success.

“To be honest I doubt very much whether he’ll be available for the next test,” Bayliss told reporters.

“We’ll have to wait and see how bad it is and make a decision on the one-day and Twenty20 series (following the tests).

“But at this stage it looks like we have to make a replacement there heading into the last test,” Bayliss added.

South African squad: AB de Villiers (captain), Kyle Abbott, Hashim Amla, Temba Bavuma, Stephen Cook, Quinton de Kock (wkt), JP Duminy, Faf du Plessis, Dean Elgar, Morne Morkel, Chris Morris, Dane Piedt, Kagiso Rabada, Rilee Rossouw, Dale Steyn, Stiaan van Zyl, Hardus Viljoen.