Jenson Button was fortunate to escape injury after his McLaren was struck by a drain cover during practice for Sunday's Monaco Grand Prix.
While world champion Lewis Hamilton, and later the impressive Red Bull of Daniel Ricciardo set the pace in the respective 90-minute sessions at the principality, the ease in which the dislodged drain cover found its way on to this most famous of circuits will be cause for concern.
Nico Rosberg sustained a rear-left puncture after he ran over the drain cover on the exit of Sainte Devote. Jenson Button, following the Mercedes driver, then clattered into the dislodged piece of metal, causing significant damage to the front of his McLaren.
The session was immediately red-flagged with FIA race director Charlie Whiting straight on to the scene, before repair work was hastily carried out on the affected area.
Button's lucky escape was among a number of high-profile incidents ahead of the blue-riband race. Felipe Massa crashed out at turn one after he lost control of his Williams with just 35 minutes of the opening session gone. British rookie Jolyon Palmer was also in the wall on his grand prix debut at the iconic venue.
Sterling work from their respective mechanics enabled the pair to take part in the second session, but only had Renault fixed one of their cars when their other was in the wall after Kevin Magnussen crashed at the final corner.
The Haas of Romain Grosjean and Indonesian driver Rio Haryanto also clattered the barriers - both on the exit of the tunnel - while Sebastian Vettel, the four-time world champion, also sustained damage to his rear wing following a spin at Mirabeau, before later thudding into the barriers on the exit of Sainte Devote.
On Wednesday, Hamilton insisted there is no longer any tension between himself and Rosberg following their opening-lap crash at the Spanish Grand Prix a fortnight ago.
And his early marker in first practice is just what the Briton, who has not won since October's United States Grand Prix - a streak which stretches to eight races - required as he attempts to get the fraught defence of his championship back on track.
But on the basis of the second practice session, it is Red Bull who appear more than ready to take the challenge to Hamilton's all-conquering Mercedes team.
Ricciardo's best lap of one minute and 14.607 seconds was the fastest recorded on Thursday, and was easily half-a-second faster than both Hamilton with Rosberg, a winner in Monte Carlo for the past three years, marginally slower.
Max Verstappen, the 18-year-old who became the sport's youngest-ever winner following his memorable triumph in Spain, was fourth quickest nearly one second slower than his Red Bull team-mate. Vettel was ninth in the order while Button finished the second session in 10th two places ahead of his McLaren team-mate Fernando Alonso.
Final Positions after Second Practice:
1 Daniel Ricciardo (Aus) Red Bull 1min 14.607secs
2 Lewis Hamilton (Gbr) Mercedes GP 1:15.213
3 Nico Rosberg (Ger) Mercedes GP 1:15.506
4 Max Verstappen (Ned) Red Bull 1:15.571
5 Daniil Kvyat (Rus) Scuderia Toro Rosso 1:15.815
6 Carlos Sainz (Spa) Scuderia Toro Rosso 1:15.981
7 Kimi Raikkonen (Fin) Ferrari 1:16.040
8 Sergio Perez (Mex) Force India 1:16.120
9 Sebastian Vettel (Ger) Ferrari 1:16.269
10 Jenson Button (Gbr) McLaren 1:16.325
11 Nico Hulkenberg (Ger) Force India 1:16.487
12 Fernando Alonso (Spa) McLaren 1:16.723
13 Esteban Gutierrez (Mex) Haas F1 1:16.782
14 Valtteri Bottas (Fin) Williams 1:16.849
15 Romain Grosjean (Fra) Haas F1 1:16.874
16 Felipe Massa (Bra) Williams 1:17.286
17 Kevin Magnussen (Den) Renault 1:17.530
18 Marcus Ericsson (Swe) Sauber-Ferrari 1:17.562
19 Jolyon Palmer (Gbr) Renault 1:17.761
20 Felipe Nasr (Bra) Sauber-Ferrari 1:17.999
21 Rio Haryanto (Ina) Manor Racing 1:18.647
22 Pascal Wehrlein (Ger) Manor Racing 1:18.814
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