Wolff: Bottas's Mercedes F1 future to be decided in August

While the Finnish driver has shown progress this year, especially in qualifying where he has secured four pole positions, he has only managed two races wins from the first 10 races.

Although the second Mercedes seat for 2020 is likely set to go to Bottas or reserve driver Esteban Ocon, Red Bull's Max Verstappen has also been linked - but this will depend largely on performance clauses in his Red Bull contract being activated around the summer break.

Speaking ahead of the German Grand Prix, Wolff said one of the key factors being considered was to ensure that Mercedes' call is right for the team's long-term future.

"We want him to end up the season before the shutdown in a good place and put in two solid performances in Hockenheim and Budapest, and then spend some time thinking about the driver line-up for 2020 and beyond," he said.

"It is pretty unusual to announce drivers in July.

"If you want to take all the time, you properly need to assess and you can even drag it into the winter like we have seen in some other teams and it was a standard in the past.

"For us it is not only about making the right decision for next year but looking ahead and this is why we agreed that we will take the decision in August going forward, but it doesn't necessarily mean we will announce it in August."

Wolff said other teams were interested in Ocon for next year if the team elected not to take him, but that could then mean losing hold of the Frenchman for a few years.

"As we all know it was an unfortunate situation last year that Esteban fell between the chairs," added Wolff.

"He could have chosen between two seats and in the end nothing came out.

"From our perspective everyone knows about his driving capabilities for Mercedes.

"Valtteri is showing some very strong performances and merits the seat but equally Esteban has shown that in the past and is a great addition to the team.

"He contributes a lot a lot behind closed doors, he drives the sim overnight on race weekends, he comes in here Saturday and gives us input and he is a great kid overall.

"Putting a Mercedes young driver in the car would be interesting as well.

"Having said that, there is interest for Esteban among other teams and we need to carefully make a decision for ourselves and with the other interested parties, not only for our own benefit but also for Esteban's benefit.

"If it would be that we were taking a decision in favour of Valtteri, it clearly also means that somebody else would continue to develop him [Ocon] and would mean we would lose our hand for a year or two or more on Esteban.

"These are the consequences of that decision."