'Bibo' had to be helped off the field during Bucs' 3-3 draw with Maritzburg United at Harry Gwala Stadium this past Saturday.
At the time of the incident, Ntshumayelo's ankle was heavily bruised and swollen, and he struggled to walk unassisted.
The 25-year-old, who is set to undergo a scan, will be on crutches for the next few days.
"He had a bit of a nasty tackle. It was a tackle in my opinion that deserved a red card... in my opinion," says Pirates coach Eric Tinkler.
The Sea Robbers will tackle Jomo Cosmos this Saturday before hosting Chiefs at FNB Stadium on January 30.
Ntshumayelo impressed in Pirates' 3-1 win over Amakhosi in the reverse fixture at the same venue on October 31.