Sergio Perez's Azerbaijan Grand Prix podium could be in jeopardy after the Force India Formula 1 driver was summoned to the stewards over improper DRS use.
Perez came back from having to pit for repairs following a first-lap hit from Sergey Sirotkin to take third place in Baku, pouncing on Sebastian Vettel when the erstwhile F1 world championship leader flat-spotted his tyres trying to attack Valtteri Bottas for the lead at the final safety car restart.
But having held off Vettel's retaliation attempts to claim his first F1 podium since the same event two years ago, Perez has been called to the stewards over two allegedly illegal uses of DRS at 16.53 and 16.55 local time, during the middle of the race.
Eighth-place finisher Lance Stroll and Kevin Magnussen, who ended up 13th after a late incident with Pierre Gasly, are also under investigation for the same issue.
Perez already had to serve a five-second time penalty during his second pitstop for passing before the safety car line at the restart from the first caution period early in the race.
He felt his late battle with Vettel was among the best driving of his career.
"I think today I did the two best laps of my whole career," said Perez. "The last two laps with Sebastian behind with cold tyres was so difficult.
"I was on supersofts and had to keep a close rhythm to keep close to [Kimi] Raikkonen to make sure Seb didn't get close enough. I am speechless."
Force India had filled the fourth row of the grid in Baku qualifying, before both drivers were involved in first-lap incidents.
Esteban Ocon had to retire on the spot following a clash with Raikkonen.