Roberts twisted his leg in a tackle and limped off ten minutes into Cardiff Blues' 26-20 Heineken Cup away win over Racing Metro on Friday.
Coach Justin Burnell said afterwards "nothing major" had been sustained, but it is predicted he will be forced to miss Friday's Heineken Cup fixture against London Irish.
Club physios believe he will be able to face Aironi the following week, while they have allayed fears he would be missing from action still when Australia - who defeated Wales to claim World Cup third-spot - come to Cardiff on December 3.
"Jamie has just twisted his leg in a tackle so at the moment we think that's just a bit of a strained groin," Burnell said.
"But there's nothing major there."
Roberts was making his first appearance for the Blues this term after impressing in New Zealand, but physiotherapist joined Burnell in playing down the severity of the injury after a scan showed only some swelling to the knee.
He said: "It is expected that he won't play this Friday.
"[His knee] a little bit swollen, but it is not thought to be a serious injury."