Mercedes boss Toto Wolff admits Valtteri Bottas is in an "uncomfortable position" at the team in 2017 due to the fact his contract only runs until the end of the year.
In January Bottas was confirmed as Nico Rosberg's replacement, filling the seat left vacant by the reigning world champion's shock retirement in December. The last-minute nature of Bottas' deal meant he was only given a one-year contract, leading to speculation about whether he will remain Lewis Hamilton's teammate in 2018.
Though Mercedes is in no rush to confirm its line-up for next year, Wolff has been impressed with Bottas, who won his maiden F1 race at the Russian Grand Prix in April.
"Of course it's an uncomfortable situation for him with quite some pressure," Wolff said. "When we decided to make Valtteri the offer, he knew that we would be taking our time with the decision going forward because the driver market is more open in 2018 and beyond -- 2018 and 2019.
"That's why we will not rush into a decision, but continue to work with him and see how that pans out. But generally the view of the team is that he's done a good job. The call he received was pretty late, he's driving against one of the best drivers in Formula One that has been with the team in his fifth season and he's had a pole position, won a race in Sochi in a very dominant way and he's had the more difficult races.
"But overall his performance on-track and the way he has integrated with the team was very positive."
Before Rosberg's retirement, it looked unlikely Bottas would break into a top team before 2018 having been overlooked by Ferrari two years ago. Wolff thinks the Finnish driver has already proved his decision to take on the one-year deal was the right one.
"He has taken a decision to leave Williams and join Mercedes in a one-year deal. I think that the perception of him as a racing driver has gained. He's won a race rather than lost, so I think it already paid out."