Eric Boullier insists it is too early to say when or even if Robert Kubica will return to Formula One.
The injured Pole is now out of hospital and reportedly spending up to seven hours per day on his rehabilitation, particularly to restore the functionality of his right hand that was almost severed in a rally crash in February.
"I don't know when or if Robert can come back," Renault team boss Boullier is quoted by the German news agency SID in Turkey.
"He is making very good progress, but it is a long way back from such a serious injury. So I don't want to make any predictions," added the Frenchman.
On the other hand, Boullier said he is very happy with Kubica's substitute, Nick Heidfeld.
"He is working very well and is very communicative," he said of the 33-year-old German.
"What I hope and expect for this season is to be regularly in the points and to occasionally go to the podium," added Boullier.