Sebastian Vettel is in a "pretty grim" situation as he will not win another Formula One title unless he joins a top-three team, according to Mario Andretti.
Four-time champion Vettel will leave Ferrari at the end of the season but has seen a potential return to Red Bull in 2021 ruled out by team principal Christian Horner.
A switch to Mercedes has been mooted due to Valtteri Bottas only being contracted until the end of the campaign, with Racing Point his next best option after Fernando Alonso agreed to join Renault.
Vettel said prior to the Styrian Grand Prix this weekend that he could take a year out or retire, with 1978 F1 champion Andretti suggesting the German's glory days will be behind him if he settles for a car in the midfield.
Andretti told Stats Perform News: "Well the clear situation is this: you're not going to win a title unless you're with one of the top three teams in Formula One. Historically it's been the same, always.
"[Vettel] needs to be with that type of equipment and it looks like all the seats are filled for the foreseeable future, so the situation is pretty grim for him at the moment.
"I feel very bad for him but, honestly, I think somehow he's going through a difficult period let's just say, and it shows that he feels the pressure and he just needs to settle down somewhat because he's certainly a capable driver.
"You don't win four world championships if you're not capable of dealing with a difficult situation.
"He has a very valid team-mate there with Charles [Leclerc], no question, but again, his future is pretty much set as we know it and it's all about a valuable seat opening up by the time he's free from this contract.
"That's the big question. Other than that, it's pretty grim for him quite honestly."
#Quali #Seb5 P10 @Charles_Leclerc P11 #essereFerrari #AustrianGP pic.twitter.com/37JKQaf2CH
— Scuderia Ferrari (@ScuderiaFerrari) July 11, 2020
Carlos Sainz will leave McLaren to replace Vettel at Ferrari.
After finishing fifth at the season-opening Austrian Grand Prix last weekend, Sainz on Saturday qualified in third for this year's second race at the Red Bull Ring.
Andretti said: "Now should be the time for him to judge himself, with that level of equipment even if it's Ferrari, but somewhat still capable of being top three, to see if he can race up to the job.
"He's going to be going up against Charles who is already established there so it's going to be a tough situation. However, that's what you're supposed to do, you're supposed to measure up.
"This will be the chance and the big opportunity of his career to demonstrate that he belongs there at the very top.
"It's interesting to see because he has a future ahead of him so I'm glad to see he's having that opportunity, I think he deserves it and that's another area for us to be able to watch closely and see how it develops."