Pascal Wehrlein and Valtteri Bottas have each been praised by Mercedes head of motorsport Toto Wolff, who says the team are ready to take a "brave decision" when selecting a replacement for retired world champion Nico Rosberg.
The Formula One constructors' champions are seeking a partner for Lewis Hamilton after Rosberg made the surprising decision to walk away from the sport following his maiden title win.
Wehrlein, currently without a 2017 seat following a season with Manor, has impressed Wolff as a junior driver for Mercedes, while Bottas has a long association with the Austrian.
Earlier this week, Wolff acknowledged two-time world champion Fernando Alonso is among those being considered as a replacement for Rosberg.
However, the Mercedes chief's latest comments suggest 22-year-old Wehrlein is very much in contention for the vacancy.
"Clearly, with Nico taking the decision quite late we are in a bit of a compromised situation because if we had known three months ago there were more options available," Wolff told Sky Sports F1.
"Maybe we need to make a brave decision in the same way Nico has made a brave decision."
Discussing Wehrlein and fellow youngster Esteban Ocon, who beat the German to a place in Force India's 2017 line-up, Wolff added: "Sometimes in life things turn out differently than you expected.
"I think in terms of performance, both have had great races in the past, had solid performances with Manor, and they deserve a future in Formula One. Therefore I consider both of them as future stars."
Wolff also talked up Bottas, amid suggestions from ex-F1 world champion Damon Hill that the Finn could be lured to Mercedes from Williams as part of an exchange deal involving Wehrlein and discounted engines.
"Besides the personal relationship, where he's a very likeable and intelligent driver, he's also somebody who is very, very fast," said Wolff of Bottas.
"But he's with Williams now, the lead driver, and is very important for the combination with Lance Stroll. Claire [Williams] and her team very much rely on him."