Toto Wolff has said that Valtteri Bottas has "no excuses" this year as he pushes for a new Mercedes contract.

Bottas had a mixed first year with Formula 1's top team, but he is aiming for a full title assault in 2018.

At the same time, he was only given a new single-year contract.

However, Bottas insists: "The pressure is now much less.

"I have gone through one season with Lewis [Hamilton], and the team is now familiar to me. At my best level I can get poles and win races.

"Last February, I had to learn about the team but now I can focus just on improving the performance. I'm able to concentrate on driving a lot more."

Hamilton said it is obvious that many other drivers want his seat, but he will focus only on driving as well as possible in 2018.

"At this stage, contractual issues seem completely secondary," said Bottas, according to Iltalehti.

"It will only be considered a little later. My goals are so high that they eliminate any external pressure.

"If I achieve them, there will certainly be no problem with the contracts."

When asked if he is worried that an improved Bottas is targeting the title this year, teammate Hamilton said in Barcelona: "No.

"But I'd say that about everyone. It has nothing to do with Valtteri.

"He made a great impression in the last races last year and I expect him to be in top form. But I am too."

Finally, team boss Wolff said that he expects Bottas to challenge Hamilton in 2018.

"If he can step up and challenge Lewis, he certainly has his place among the best Formula 1 drivers. If he does not, he will notice that there are no excuses," he said.

The new season gets underway with the Australian Grand Prix later this month.