Mercedes driver Nico Rosberg said he "cannot totally be friends" with team-mate and rival Lewis Hamilton as the pair go through a difficult period.
The rivalry between the duo was intense during 2014, when Hamilton won the Formula One world title ahead of Rosberg, and it has continued into this year.
Rosberg accused Hamilton of deliberately slowing him down at the Chinese Grand Prix, while the Brit continued the war of words by suggesting his German team-mate did not always try to win.
Speaking to the Daily Mail, Rosberg said he was never angry - but he admitted his relationship with Hamilton was in a tricky position.
"Lewis and I are going through a difficult period. We cannot totally be friends. We go through ups and downs," he said.
"We are only speaking when we need to but sometimes we have a laugh together. We have so much to do with each other.
"We karted together. We are here together. I am not an ice man, either. Things can get to me but I do not get angry. I am rational. You won't catch me getting very emotional."
Hamilton is 13 points clear atop the drivers' standings through three races, and looks set to extend that after taking pole at the Bahrain Grand Prix.
Rosberg was unwilling to give details about how Hamilton irritated him.
"I know exactly how he is functioning. I understand him really, really well. All his attitudes. I can tell why he is doing whatever he is doing," he said.
"Sometimes he annoys me [with] some character traits."