Sebastian Vettel’s slim title hopes may have taken another hit after he was summoned to the stewards following first practice at the U.S. Grand Prix. Vettel is being investigated for speeding under red flag conditions during the opening practice session, which has the potential to carry a three-place penalty on Sunday’s grid. The incident happened 40 minutes into the session after running was suspended due to gravel being dragged onto the circuit by Charles Leclerc‘s Sauber.

When a red flag is shown, all drivers are required to drive to a reduced pace and return to the pits. It seems as though Vettel’s Ferrari was clocked exceeding that pace and, if that was the case, it is likely to be a fairly straightforward decision to impose a penalty.

A similar incident occurred at the last round in Japan when Esteban Ocon was given a three-place grid penalty for the same infringement. Daniel Ricciardo also received a three-place penalty at the opening round in Australia under similar circumstances.

Vettel needs to finish within eight points of title rival Lewis Hamilton to keep his championship hopes alive for another round and a three-place penalty would create another obstacle for the Ferrari driver, who has struggled to match Hamilton for pace at the last four rounds. Vettel finished the wet practice session in fifth place, nearly two full seconds off Hamilton’s fastest time.

With a penalty looming for for the German, whatever was left of his championship challenge, is now over. His only hope lies in a potential rare retirement for Lewis Hamilton, but it is highly unlikely that such an event will occur.

Free Practice 1 was a soggy affair, but it did little to hinder Lewis Hamilton who was 1.6 seconds faster than Valtteri Bottas. Ferrari’s day got even worse as both Red Bulls ended the session ahead of them.