Mercedes boss Toto Wolff says Niki Lauda's death has left him on the verge of crying every 30 minutes.
The Silver Arrows team principal is set to oversee Lewis Hamilton's assault on the Monaco Grand Prix this weekend.
But following the British driver's withdrawal from yesterday's press conference in Monte Carlo – the world champion saying he was too emotional to speak about Lauda's death – Wolff opened up for the first time about the loss of his Austrian compatriot.
Lauda, who won three world titles and joined Mercedes as non-executive chairman in 2012, died on Monday night in Zurich. He was 70.
"The last 48 hours have been terrible," said Wolff, who cancelled a scheduled media session here on Wednesday. "I feel like a zombie. Every half an hour, I keep looking at pictures of him with tears in my eyes because he is not here anymore.
"We knew that it wasn't going well in the last days and it would be a matter of time before we received the message.
"I got a text from Niki's wife Birgit on Monday evening and since then I have not been myself.
"It feels so surreal to be in a Formula One paddock with Niki not alive anymore.
"Maybe Lewis and I are in a similar frame of mind because we have lost a friend. Lewis and Niki are bound together by an additional link, and that is the one of being multiple world champions. Only very few have experienced that, to win over several years against the best."
Wolff and the rest of the Mercedes team were sporting black armbands as opening practice got under way on the streets of Monte Carlo on Thursday. He was speaking against the backdrop of rolling imagery of Lauda in Mercedes' hospitality suite.
The world champions head into the sixth round of the season following an unprecedented perfect start – five one-two finishes from as many races.
For our Chairman and for our friend. pic.twitter.com/GsuFeoIPGi
— Mercedes-AMG F1 (@MercedesAMGF1) May 23, 2019
"The last time I spoke to Niki was on the phone after the fourth race in Baku," added Wolff. "He said 'keep on going, it doesn't get any better than this'.
"There is just a huge, huge black cloud over us. We have lost what was the heart and soul of Formula One.
"But Niki, watching on, will be interested to see how this weekend goes on track, and nothing else."
Hamilton heads into Sunday's race holding a seven-point championship lead over his Mercedes team-mate Valtteri Bottas.