Paul di Resta is now in reigning world champions Mercedes’ sights.
It comes after the former Force India driver performed admirably as he stood in for the unwell Felipe Massa in qualifying in Hungary.
It is believed Massa is suffering from Labyrinthitis, a virus that is sweeping the F1 paddock and struck down British commentator Martin Brundle at Silverstone.
"He’s having vertigo and has some problems with his ears but I don’t know the medical terminology," said Claire Williams. "He (Massa) will have some more tests after the weekend."
What the Massa case has highlighted is that many F1 teams do not have a reserve driver on standby.
Indeed, although Williams’ official reserve, di Resta does not seem an obvious choice, as he has not raced in F1 for years and was in Budapest as a commentator for British television.
One issue is the F1 super license system, with many younger but more appropriate potential stand-in drivers unable to get FIA permission to race.
Red Bull’s Dr Helmut Marko said the current system is "not user friendly" and McLaren’s Eric Boullier said the di Resta situation is even a "safety risk".
Boullier said: "Technically we still have Jenson Button, but we would probably have to ask Ferrari if we needed someone at the last moment."
Indeed, Ferrari reserve Antonio Giovinazzi has a super license, with even reigning champions Mercedes not having an official reserve at races on standby.
"We would put Niki (Lauda) in the car," Toto Wolff joked.
"We would probably use Paul (di Resta)," he added. "He did an incredible job, having never driven that car and only being seven tenths slower than Lance Stroll.
"Perhaps he has revived his F1 career today," said Wolff.