The rivalry in the Mercedes garage between Nico Rosberg and Lewis Hamilton is likely to continue as long as they're the fastest cars on the grid, according to Robert Kubica.
Kubica has known both drivers since their karting days, and during an exclusive interview with Autosport, the Pole admitted that tension within a team invariably exists when a World Championship title is on the line.
"When you are only fighting against your team-mate, it can get quite difficult," Kubica told Autosport.
"If there are some other drivers close, you have to focus to finish second, but in the current situation Nico and Lewis need to have a very bad day not to finish in the top two.
"But when you have more competition, you have to avoid bad days, as if you are sixth there is a bigger loss of points.
"So this might help the relationship but now they know they are only driving against each others as the others aren't something to worry about because Mercedes has such a big advantage.
"It's not easy, but they know each other very well and I think it is not as bad as the media would like to see it.
"But it would be tense because that is normal when you are fighting for wins and the championship."
The former BMW-Sauber driver added that Toto Wolff and Niki Lauda, the Mercedes bosses, have an unenviable task ahead of them if they are going to prevent the rivalry from exceeding bowling point.
"In the current situation, Toto and Niki have a big role," Kubica continued.
"I remember I was watching the race in Bahrain and there was a shot of Toto on the pitwall, for sure I would not like to be in his position.
"It is a delicate situation because you have two great drivers with a big car advantage over the others."
The 29-year-old Kubica also believes from a pure speed perspective, Hamilton has the superiority, but noted that Rosberg's evolution as a driver is impressive.
"If you ask 100 people who know Nico and Lewis, they would always tend to say Lewis is the faster guy," said Kubica.
"But speed is not the only important thing in F1.
"Overall, Nico has improved a lot over the past two or three seasons, especially how he's approaching the races."