Sebastian Vettel must rise to the challenge in 2020 to ensure he can prolong his Formula One career, according to David Coulthard.
The Ferrari driver is under pressure going into the new season after being outshone by new team-mate Charles Leclerc last year.
Four-time world champion Vettel last claimed the drivers' championship in 2013, with his Ferrari seat more vulnerable than that of Leclerc, who has signed a new long-term deal.
Coulthard believes the 32-year-old's quality is beyond doubt but fears for his career if he underperforms in 2020.
"He's a class driver, you don't win those championships without being so," Coulthard said to Omnisport about Vettel.
"We have seen in previous years, his last year at Red Bull, he lost a bit of consistency and performance, but he was able to bounce back at Ferrari alongside Kimi Raikkonen.
"Let's see if he can bounce back this year. It's in his hands. We know Charles is fast, we know he's able to get those qualifying results and race results, but Seb is a four-time world champion.
"This year is a very important year for him to establish if we will see more of him."
Coulthard is concerned Vettel would not have another realistic option if the Italian team opt not to retain him.
"I just don't see where he could go logically at the level of expectation in terms of salary and what-have-you," added Coulthard.
"Red Bull seem quite set in their programme. McLaren have two young drivers. Mercedes, they don't need him. So, I think it's a little bit like Fernando Alonso, even if they want to race there isn't the opportunity for them."
Coulthard ended his F1 career at Red Bull and is hoping to see Max Verstappen challenge defending champion Lewis Hamilton for title glory this season, even if the Briton remains the favourite.
On the title race, he said: "Easy money is to say Hamilton at Mercedes but I think it's absolutely possible on paper for the world champion to come from Red Bull, Ferrari or Mercedes.
"I would love to see Max really challenge for the championship. He's got speed, he's got commitment, he's got a young, devil-may-care attitude.
"He's a breath of fresh air because he's also very open, very honest, and not kind of aloof and standing off. So I think he would be a great champion.
"Mercedes have done an exceptional job, but we can see that Ferrari have come up over the last couple of years to being real contenders and Red Bull in their new partnership with Honda are getting a few victories.
"Those three teams can be challenging for, certainly race victories, and possibly the championships."