Lewis Hamilton says there are "no more excuses" for Mercedes Formula 1 teammate Valtteri Bottas to be competitive through 2018 as he gears up for his second season with the team.

Bottas arrived at Mercedes in January 2017 as a late replacement for world champion Nico Rosberg following his shock retirement, and took three wins through his first season with the German manufacturer en route to third place in the drivers' championship.

A mid-season dip in form led to questions about Bottas' ability to take the fight to Hamilton, who went on to win a fourth drivers' championship, but the Finn is now ready for his second year with Mercedes, saying last month that he remains confident his teammate is beatable.

Asked if he expected Bottas to be harder to beat in 2018, Hamilton said: "No. But I would say that about anyone.

"It’s not just about Valtteri. Last year it was difficult for him coming into a new team, learning new ways and new controls and I think that now he’s got through that whole learning process.

"So now I think he’s going to hit the ground running. There’s no more excuses.

"He did great in the last couple of races, which was awesome and I’m expecting him to be in tip-top shape for the season.

"Do I expect him to be closer? I assume so. I have to assume he’s going to be in the best shape possible.

"But then again so am I so that’s my goal.”