Pushed hard by Ferrari this season, Valtteri Bottas reckons it is only going to "get tougher" next season as Red Bull enter the mix.
Bottas joined Mercedes at the start of this year's championship and joined the fight at the sharp end of the field.
But while his team-mate Lewis Hamilton raced to the World title, Bottas was disappointed to walk away with just two wins with one race remaining in the season.
“Only two wins, unfortunately,” he told The National.
“I was definitely hoping for more like I said, but I am glad I have proven myself and the team signed me up again for next year.
“Next year’s going to be the same thing.
“I need to again prove if I am going to stay with the team for a long time.”
The Finn, though, believes next season could be a trickier one for himself and Mercedes as, based on late-season form, Red Bull could also get involved in the championship fight.
“The season has been tough," he said.
“There have been many races that Ferrari have had the upper hand, and even lately Red Bull have been really strong so it has definitely not been like the last three years.
“It has been tough and it is only going to get tougher.”
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