Competition rules state that clubs may register a maximum of 30 players. They can register any number before the January 15 deadline and then complete the quota in a second registration window which starts two weeks before the beginning of the group phase up and lasts until August 5.
Sundowns registered 25 players before the first deadline, leaving five places for mid-year additions.
They have since added goalkeeper Thela Ngobeni in a move that was forced upon them by injury and suspension ahead of their last match against Enyimba when Denis Onyango was banned and Kennedy Mweene injured, leaving no cover for Wayne Sandilands. Ordinarily clubs try to avoid registering too many goalkeepers.
Sundowns coach Pitso Mosimane said one of the remaining spots would be taken by the new Brazilian signing Ricardo Nascimento, effectively leaving three more vacancies for any new signings over the next month.
They cannot, however, replace departing players and have seen from their original list the exit of Katlego Mashego, Ramahlwe Mphahlele and Bongani Zungu.
Sundowns' Champions League roster: