Nell assumed the captaincy for the first division final last week and led the Kings to a tense victory over the Pumas, but suffered a calf injury which may keep him out of the first leg of their promotion/relegation play-off with the Cheetahs in Bloemfontein on Friday.
Kings coach Alan Solomons told this website that losing Nell so soon after Watson would be a crucial blow ahead of such an important game.
"He damaged a calf muscle and he is in doubt.
"We missed Luke [Watson] in the final, he is a fantastic player and obviously as a leader as well, and now Darron who has done well to fill Luke's shoes is potentially out," he said.
Solomons was full of praise for the character his team showed to clinch a dramatic victory over the Pumas who they drew with in both their league fixtures this season.
"It was a final and like most finals they are tightly contested affairs, and our contests with the Pumas have inevitably been closely-run things but I am very pleased that we came away with the win.
"I think it was an appropriate game to play going into these two promotion/relegation matches," he said.
The Kings boss said that despite the Cheetahs' lengthy injury list, he does not expect depth to be a serious issue for them as they are such a well-established union.
"They are a Super rugby franchise, and they have been playing Currie Cup premier division for many years, so one would assume that there is strength in depth and we are obviously expecting a very tough game.
"This is a team that has come a long way in the season and we would all like to finish on a good note," he said.
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