Mercedes boss Toto Wolff remains optimistic over the Formula One team's chances of signing Nico Rosberg to a new deal.

Rosberg's contract with the German manufacturer runs out at the end of the season.

Wolff said both parties are committed to continuing their partnership, but are still yet to iron out a few terms. 

"We want to continue with Nico and he wants to continue with us," Wolff said on Friday ahead of the Canadian Grand Prix. 

"We are having discussions that are ongoing and very positive. We are not talking to anybody else. This is a commitment we owe to him.

"He has been part of the journey since 2010 and I am very optimistic that we will come to a solution soon."

Rosberg leads the driver standings by 24 points over team-mate and two-time defending champion Lewis Hamilton heading into Sunday's race.

The 30-year-old finished second in free practice on Friday, before dropping a spot down to third in the second session as Hamilton topped the time sheets in both.

"Generally I feel good in the car. But getting the tyres working is not so straightforward here, so that needs some further analysis," Rosberg said.

"I lost most of my time in the first sector - possibly because of tyre temperatures. So that part of the lap is the main area to work on and find some improvement for qualifying. 

"The long runs have looked good so far, though. It's been great to see so many spectators out there already today and I'm sure there will be an awesome atmosphere over the weekend."