Max Verstappen may have destroyed his chances of winning the Monaco Grand Prix after crashing out of final practice.
Verstappen lit up the time sheets with a super-quick lap of the Monte Carlo track, but then ended the one-hour session in the barriers.
The Dutchman lost control of his Red Bull at the high-speed swimming pool section, hitting the wall on entry before smashing into the opposing barrier and sustaining serious damage to the front and right-hand side of his car.
His mechanics now face a race against time to ensure his car is ready for qualifying which takes place later on Saturday.
If Verstappen fails to post a lap he will start from the back of the grid for Sunday's race.
Red Bull's pace over the weekend had appeared to put them on course to lock out the front row at a circuit where overtaking is virtually impossible.
But their hopes now hang in the balance following Verstappen's crash in the closing minutes of practice.
Verstappen's mistake marked his fourth crash in as many seasons at the principality.
He had posted the fastest time of the morning running only to be usurped by his team-mate Daniel Ricciardo, who set a record-breaking lap of the Monte Carlo track in the final moments.
Championship leader Lewis Hamilton's difficulties continued as he could manage only fifth, the best part of half-a-second down on Ricciardo, with Valtteri Bottas sixth in the other Mercedes.
Sebastian Vettel, who trails Hamilton by 17 points was third, a quarter of a second off the pace. His Ferrari team-mate Kimi Raikkonen was fourth.
- Daniel Ricciardo (Aus) Red Bull 1min 11.786secs
- Max Verstappen (Ned) Red Bull 1:11.787
- Sebastian Vettel (Ger) Ferrari 1:12.023
4 Kimi Raikkonen (Fin) Ferrari 1:12.142, 5 Lewis Hamilton (Gbr) Mercedes GP 1:12.273, 6 Valtteri Bottas (Fin) Mercedes GP 1:12.356, 7 Brendon Hartley (Nzl) Scuderia Toro Rosso 1:12.752, 8 Pierre Gasly (Fra) Scuderia Toro Rosso 1:12.761, 9 Carlos Sainz (Spa) Renault 1:12.850, 10 Sergey Sirotkin (Rus) Williams 1:12.854, 11 Stoffel Vandoorne (Bel) McLaren 1:12.874, 12 Esteban Ocon (Fra) Force India 1:12.940, 13 Sergio Perez (Mex) Force India 1:13.025, 14 Nico Hulkenberg (Ger) Renault 1:13.112, 15 Fernando Alonso (Spa) McLaren 1:13.279, 16 Lance Stroll (Can) Williams 1:13.595, 17 Charles Leclerc (Mon) Sauber-Ferrari 1:13.644, 18 Romain Grosjean (Fra) Haas F1 1:13.881, 19 Kevin Magnussen (Den) Haas F1 1:14.192, 20 Marcus Ericsson (Swe) Sauber-Ferrari 1:14.221