George Russell has detailed the "intense" 48 hours that led to his call-up to replace Lewis Hamilton at Mercedes for the Sakhir GP - revealing he was "in the bathroom" when Toto Wolff first phoned him in the early hours of Tuesday, one of 64 calls he had with various parties to conclude the deal.
Hamilton's positive test for coronavirus on Monday has sidelined the seven-time world champion for at least this weekend's race in Bahrain - the second successive event at the Sakhir venue ahead of next week's season finale in Abu Dhabi - and Mercedes have turned to the highly-rated 22-year-old Russell to fill the substantial void left by his British countryman.
But although his career is managed by the world champions, Russell is in the second year of a firm three-year contract at Williams - meaning an emergency deal for him to race for Mercedes was not the work of a moment.
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Explaining the timeline of events as he appeared in Mercedes colours for Thursday's media day at the Sakhir circuit, Russell said: "I got a phone call from Toto at 2am on Tuesday morning. I was actually in the bathroom which was slightly awkward.
"So he answered the phone and said 'George, are you in the bathroom?' I was like 'yeah, sorry I am in the bathroom!'"
"He said 'unfortunately Lewis has caught Covid. He's doing well, is healthy and feels fine', which is the most important, but then 'we want you to drive'.
Speaking to Sky Sports F1, Russell said the call-up was "a bit unexpected as we actually spoke about this last year and the start of this year about if this circumstance would arise what we would do.
"So I'm incredibly thankful to Mercedes for putting their faith and belief in me because there was a lot of work went in to making it happen.
"Logistically, getting helmets painted, getting suits made, lawyers working through the night to write contracts, amendments to Williams contract… you know, it was chaos for 24 hours.
"I had 64 phone calls in the day back and forth between everybody!"
Russell thanked Williams for facilitating the short-term switch - "Williams did not have to do this. Really grateful and thankful that they gave me this opportunity" - and wished Hamilton, who is isolating and has mild Covid-19 symptoms, well in his recovery.
Although he has not yet spoken to the seven-time champion since the news was confirmed, Russell expects to do so over the course of the weekend.
Russell's tight fit into Mercedes' car
The former F2 champion has tested for Mercedes before, most recently in Abu Dhabi last December, but never the current W11 which has won both this year's world titles at a canter.
At 185cm, Russell is also taller than Hamilton and team-mate Valtteri Bottas, who the car has been optimised around.
Asked if he fit into Hamilton's car easily, Russell replied: "Fit is one way of putting it! Do I squeeze in? I do squeeze in.
"The biggest issue is actually my feet - I've got sized 11 feet. Lewis and Valtteri have smaller feet so I'm actually wearing one size smaller boots than I would do originally.
"Not the most comfortable but I'm sure I can endure the pain... only through the 87 laps on Sunday!"
Russell said he had "no expectations" and "no pressure" heading into the weekend, adding: "If I'm a couple of tenths away from Valtteri, honestly, I think I can be pretty pleased with that."