Damp, soupy weather disrupted the Chinese Grand Prix's first free practice on Friday, delaying at least for a few hours the resumption of hostilities between Mercedes and Ferrari.
With low clouds hanging over the Shanghai track, the morning session was red-flagged after just a few minutes as a safety precaution, resumed briefly, but then halted again for good.
Formula One officials cited the fact that the medical helicopter would be unable to land at designated hospitals due to the inclement weather. Even the local airport had to be closed, the FIA noted ominously.
More than half of the drivers got a crack at the boggy circuit with Max Verstappen of Red Bull getting around the quickest.
But title rivals Lewis Hamilton and Sebastian Vettel were unable to get on the track and it remained to be seen weather the afternoon session would proceed as planned.
Hamilton and defending champions Mercedes have vowed to bounced back after their wake-up call in the season-opener in Melbourne two weeks ago, where Vettel steered his Ferrari to a commanding victory.
Hamilton, a three-time world title winner, recalled the "wheel-to-wheel" battles of his go-cart driving days in saying he looked forward to a season-long fight with Vettel.
"I yearn for those kinds of battles. I'm dying for that day to come again and I hope that happens with me and Sebastian," said the Briton.
With yet more wet weather forecast for the weekend, times were slow as teams ran full wets on Friday.
It was treacherous going for Kevin Magnussen of Haas, who spun out twice, and Renault's Nico Hulkenberg beached his car on a gravel embankment and had to abandon it.
Ferrari have shown impressive early pace, with 2007 champion Kimi Raikkonen taking fourth in Australia and signs pointing to another tight battle between the two top teams in China.
Newly introduced wider cars and fatter tyres of 2017 appeared to make overtaking harder in Melbourne, but Shanghai's longer stretches could make for more lead changes.