Renault's Alan Permane, head of trackside operations, says he never had any doubts that Robert Kubica would be quick during his recent Formula 1 test, despite the Polish driver not having driven an F1 car since 2011.
Kubica recently took part in a test driving a Lotus E20, supplied and run by Renault, in which he completed 115 laps of the Ricardo Tormo Circuit.
The Pole says he is now targeting a "proper comeback" and Permane reckons Kubica showed he has what it takes to keep pushing for just that.
"I had no doubt that he was still fast, and is fast," Permane told Polish TV network Eleven Sports, adding: "My only fear was whether he could drive."
Kubica suffered a serious injury to his right-arm in a rallying crash, resulting in limited movement, but it didn't pose a problem according to Permane, though it could still be a different matter at other circuits.
Watch: Robert Kubica returns to action in a Formula 1 car during Valencia test
"I can only say that on Tuesday in Valencia he did a fantastic job. I did not know, and I don't think he knew, whether he would be physically able to drive and, most of all, whether he would be able to drive a lot [of laps].
"Honestly, it went very well. He was quick. He did long runs, shorter runs, qualifying runs, we did race simulations, and everything went very well.
"[But] there are many other circuits and only he knows if he has physical limitations on other circuits, so if this continues, then it will be another step."
When asked what the next step was, Permane said Renault had nothing planned, but didn't rule out further tests.
"All I can say is that nothing else is scheduled at this moment, but I would not say that we will not do something again in the future."