Mathews' hamstring injury flared up after Sri Lanka's 12-run defeat to Zimbabwe on Wednesday.
RCB have retained Virat Kohli, AB de Villiers and Sarfaraz Khan in the IPL auction.
Rahane was seen sweating it out at nets in Johannesburg.
The IPL auction for the 2018 edition will take place on January 27 and 28 in Bengaluru.
Results summary of the Syed Mushtaq Ali T20 Trophy 2018.
Ravindra Jadeja decided to play spoilsport.
MS Dhoni will lead Chennai Super Kings after a gap of two years.