Mercedes pair Lewis Hamilton and Nico Rosberg suffered a complete breakdown in their relationship as they duelled for the Formula One world drivers' championship i 2016, according to the team's non-executive chairman Niki Lauda.
The pair were at loggerheads throughout the campaign during a bitter battle for the world title. After Hamilton won the crowns in 2014 and 2015, it was Rosberg who took his first and only F1 title before retiring at the end of the campaign.
But according to Lauda – himself a three-time world champion – communication between the pair was virtually non-existent towards the end of their spell at Mercedes, so much so that it jeopardised the team's success.
"They had no relation, which is always bad," Lauda told journalist Graham Bensinger. "They were so bad that they didn't even say hello in the morning. I don't expect them to have breakfast together if they don't like each other, I don't expect them to sit down and have breakfast, but the relationship was really bad. It affected Lewis mainly and Nico [as well], so it was fine but not easy.
"Lewis got so upset that even on their performance sometimes they lost because they're playing tricks on each other. One wouldn't show the other one what setup he is using which is bad for the team again. They played all the tricks you can do, which I can understood, but for the team it was pretty tiring."
Hamilton and Rosberg's tempestuous history was further inflamed at last year's grand prix in Barcelona when the pair crashed into each other, forcing them both to retire. Reigning champion Hamilton was eventually blamed for the collision but it led to Mercedes threatening to terminate their contracts if another such incident occurred.
"We had huge competition in the team which was sometimes too much," he added. "We put some regulations in, we told them -- especially in Barcelona when the pushed each other off the track -- we said this was unacceptable for Mercedes and one of you guys has to win [the race] you cannot push each other off.
"We had some rules put in, that you are not allowed to [do that] and you have to pay a penalty if you do it again or we will think of releasing you from your contract, because we are team players here and we cannot destroy each other. This was the thing. Toto came up with some good rules and we had peace again. We fought hard and the accidents got reduced between them."
Just a week after being crowned F1 champion, Rosberg shocked many by announcing his retirement from the sport in order to spend more time with his family. He remains a Mercedes ambassador and has attended a handful of races this season but Lauda believes the true reason behind the decision was the pressure exerted by teammate Hamilton.
"I think he retired because the pressure of Lewis was too hard for him to cope with in the future," stated Lauda. "It was tough for him the whole [final] year because Lewis was the world champion and he got beaten. He looks very happy, he makes no sign or any regret. He seems ok. He took it all out because it was to prove to himself that he could be world champion, like his father, and as soon as he does it he has no motivation to continue."