A former F1 driver thinks 2019 will certainly be Valtteri Bottas' last season at Mercedes.

Bottas is under intense pressure this year, as he is out of contract at the end of 2019.

When asked if Esteban Ocon - who is in Barcelona observing the tests as Mercedes' new reserve - will replace Bottas for 2020, Marc Surer told Speed Week: "Yes, I believe so.

"Otherwise, the Mercedes junior programme is not working. They have to do that," he said.

One person hoping Bottas stays put is probably Lewis Hamilton, his current teammate.

The five time world champion says he has an "excellent working relationship" with the Finn.

"We communicate constantly and cooperate normally, and I don't remember that sort of relationship with any other teammate," said Hamilton.

"Thanks to his character, we have a great atmosphere in the team and we have successfully defended the championships since he has been here," he added.

Bottas, though, is determined not only to secure another contract, but to beat Hamilton in 2019.

When asked about the 'new' Bottas, Hamilton smiled: "All I've seen is that he has a beard.

"I'm not the type of person who has big expectations, but I can assume that he is more aggressive this year," he said. "He weighs more and has trained hard.

"He will definitely know what things he needs to focus on," Hamilton told Finland's MTV.

"It takes time to really get used to a team and he has helped us a lot. I'm sure he wants to be stronger this year and I hope he is.

"He's probably the most humble driver I've worked with and he's easier to work with than Nico (Rosberg)," he said. "It's easy to work with a Finn."