Marcus Ericsson said he and Sauber team-mate Felipe Nasr put their rivalry aside ahead of the 2015 Formula One season. 

The two became rivals after sharing a number of battles from their GP2 days in 2012 and 2013, before being paired up at Sauber. 

Ericsson said the two were far from "best buddies", but have developed a working relationship at Sauber. 

"Going into this season it was into the unknown because me and Felipe had a bit of a history in GP2," Ericsson told Autosport.

"We had some tough battles and we were maybe not best friends there but to be honest, we've been working well together.

"We're not best buddies, but I don't think there is any reason to be that as team-mates.

"But what we do well is that we can discuss things and we usually do that for every session.

"That is important especially in a small team where we don't have the resources to throw things on the car."

The partnership could have been ruined after the two collided at the United States Grand Prix, but Ericsson said they resolved the situation after the race. 

"In Austin, we had a bit of a disagreement there but after the race we had a chat about it and then we moved on and it was 100 per cent fine," the Swede said.

"That is a strength, too. I'm happy he is staying and we can continue working together next year."