According to the Football411 website, Mphela was admitted to hospital on Tuesday after the vehicle he was travelling in collided with a delivery truck in Pretoria as he made his way home from training.
Sundowns spokesperson Kabelo Mosito reportedly said the Bafana Bafana striker's car was written off, but he was fine to leave hospital after undergoing tests.
The Brazilians have since issued a statement saying 'Killer' was excused from training on Wednesday, but he will be at Chloorkop in preparation for Saturday's opening PSL clash at Bloemfontein Celtic.
"We have assessed Katlego and we are glad to announce that the player has not suffered any injuries or bruises, which means the player is fine and will resume training on Thursday," team doctor Carl Tabane said on the club's website.
"We have decided to give him a day off and when he reports back to training on Thursday we will then reassess him to make sure that everything is ok."
Downs goalkeeper Thela Ngobeni was also involved in a car accident last month ahead of the club's pre-season trip to Ghana, but suffered no major injuries.