Former F1 driver Timo Glock has urged Lewis Hamilton to sign a new Mercedes contract.
Mercedes boss Toto Wolff this week said he wants to discuss the extension of Hamilton's contract, which runs out at the end of 2020, after the current season.
Hamilton's only real option for 2021 would be Ferrari, but Glock said the 34-year-old should stay in silver.
"He can only lose if he changes," the former Toyota driver told the German news magazine Focus.
"If he cannot make Ferrari world champion, then his five or six titles will be worth less - because he would always be judged on his most recent years.
"The smartest option for him is to write history with Mercedes," Glock added.
In the same vein, Glock thinks the pressure on Ferrari's Sebastian Vettel continues to rise.
"With each passing year it gets harder, because the pressure keeps getting higher," he said.
"Ferrari has had a good package in the past two years, not as strong as Mercedes, but there were too many races where points were left behind.
"They have to do it next year, otherwise it will be very difficult for Vettel to stay motivated."
Glock also thinks Ferrari's current driver lineup is a distraction.
"Leclerc is really strong, which means that Vettel also has to battle internally - and that's a distraction from Ferrari's real ambition, which is the world championship," said the German.
