Flanker Kolisi has left the Parisian outfit for the Sharks in Durban after just the first year of his three-year contract with his family reportedly homesick in the French capital.
The 33-year-old two-time Rugby World Cup winner's decision leaves Lancaster with the likes of France internationals Cameron Woki and Jordan Joseph as well as Kolisi's newly-arrived compatriot Hacjivah Dayimani as his back-row options.
"I think we'll wait because we've got some very good back-row players that I have confidence in," Lancaster told reporters.
"With the Top 14, we need to assess the injuries and then make a decision.
"We have space in the salary cap," the former England and Leinster head coach added.
Six-time French champions Racing, who have been bolstered by the signing of former England captain Owen Farrell, lost at Castres in their Top 14 season-opener last Saturday and host Clermont this weekend.
