Daniel Craig's Bond drama
Daniel Craig and Sam Mendes reportedly had a number of creative differences on the set of 'Spectre'.
Although the paid had a good personal relationship, they are said to have had very different ideas on the James Bond movie, which led to tension on set.
A source told The Sun on Sunday: "Daniel and Sam were best buddies when they first started working together and you would constantly see them laughing and joking.
"But after filming had been going on for a while, things started to change.
"There were a few areas in which they had very different creative opinions and their friendship did become strained.
"There were jokes that you could cut the atmosphere between them with one of Bond's knives.
"Both are hugely respected and were never unprofessional. They played their parts brilliantly and produced one of the best Bond films.
"But it wasn't the easiest of times for them."
Meanwhile, Sam also directed 2012's 'Skyfall' but insisted last year that it was time for him to step away from the franchise.
He said: "It was an incredible adventure, I loved every second of it. But I think it's time for somebody else.
"I'm a storyteller. And at the end of the day, I want to make stories with new characters."
He has also said: "There is a sense of completeness that wasn't there at the end of Skyfall, and that's what makes this feel different. It feels like there's a rightness to it, that I have finished a journey.
"What is important is, not doing it is not a negative. It's not me saying, 'I don't want to do this.' What it would be is me saying, 'I really want to do this story.' There are other stories to tell."