Centre Justin Geduld and flank Roelof Smit are both doubtful for the Junior Springboks' last match at the IRB Junior World Championship on Sunday.
They face New Zealand in the third-place play-off in Vannes, France.
Both players sat out training on Friday because of troublesome knees and will in all likelihood not be considered for the match 23, which will be confirmed on Saturday.
The Baby Boks and the Baby Blacks clash both suffered defeats in the semifinals.
Wales and England will contest the Final, the first time the JWC final match will be determined by two European teams.
South Africa, the 2012 champions, beat England in the pool stages, but lost in heartbreaking fashion against Wales, who denied the Junior Boks a second successive Final appearance when they scored a last gasp converted try.