Former F1 driver Giedo van der Garde has urged Max Verstappen to stay put at Red Bull-Honda.
In recent days and weeks, it has emerged that the Dutch driver has a performance-related exit clause in his contract that might theoretically allow a move to Mercedes for 2020.
But van der Garde, who drove for Caterham in 2013, said Verstappen should stay where he is.
"I think he's good at Red Bull," he told De Telegraaf.
"Let's not forget that Max is still very young. And Red Bull and Honda are really on the move. I expect them all to take more steps together."
Verstappen, 21, is the only non-Mercedes driver to have won a grand prix in 2019, after beating Charles Leclerc to the flag in a thrilling Austrian GP two weeks ago.
"I think he should just serve out his contract, and if it really goes in the right direction, he should consider extending it," fellow Dutchman van der Garde added.
"They are crazy about Verstappen at Red Bull, who gave him the chance in Formula 1. I think both sides are very loyal. It's all about Max at that team. That is also worth something," he said.