The Yamaha rider sits 23 points behind title rival Francesco Bagnaia heading into Sunday’s race, with the pair lining up fourth and eighth respectively.
Quartararo must win the race to have any chance of clinching the title, while Bagnaia just needs to finish 14th.
Marquez, who starts second, says Quartararo will be “aggressive” and that though he hopes the reigning champion doesn’t crash into any other riders, he would be understanding if he made contact with him.
The Honda rider said: “So I know that Fabio tomorrow will push a lot, he must push. If he crashes and hits another rider… if he hit me, I will understand.
“I don’t want, but I will understand, because he’s fighting for a world championship, not for a race.
“So I know that he’s smart but he must do the correct work, he will attack, everybody will attack, especially Ducati riders will attack tomorrow because it’s the best way to help Pecco.
“But I want to do a good race too, to me it's another race, but tomorrow the two guys are Pecco and Fabio, so everybody will pay attention about these two guys tomorrow.”
Jorge Martin, who took his third consecutive pole position at the Circuit Ricardo Tormo on Saturday, likewise said he expects Quartararo to be aggressive.
Asked what the first corner action would be like, the Pramac Ducati rider said: “Well it depends a lot on the start, no? For sure, I hope to start well, but we all know Fabio will be aggressive.
“I hope he doesn’t crash into another rider, this is the only thing I can ask for because we all will be aggressive. This will be the same for everybody.”
Martin said he will “try to make my own race,” adding: “Fabio is with me, I will see. If he’s fast, I will follow him, if he’s slow I will try to pass him. For me it’s a normal rider.
“For sure we are careful always, and I’ve been careful always with Fabio and Pecco. It’s not a thing that is Pecco or Fabio, I try to be always clean and for sure tomorrow with them we need to pay attention because if it was the opposite for sure I would like the same.”
Bagnaia’s team-mate Jack Miller, who starts third for Sunday’s race, said he will behave as he would with any race and said MotoGP is an “individual sport”.
Outgoing Ducati factory rider Miller, who moves to KTM for 2023, said: “At the end of the day, you don’t wanna hit anybody, that’s not the objective for any of us.
“But at the end of the day, it’s an individual sport, so if we’re racing, we race like it would be last week or Qatar.
“You’re racing a motorcycle but for sure you try to always take care. Don’t get me wrong, I’m not hitting people or doing anything like that on purpose, that’s for certain.”
Miller struggled during qualifying at the Malaysian Grand Prix two weeks ago, starting 14th before making his way through the field to finish sixth. The Australian said his Valencia race “can’t be worse than last week”, when he was engulfed in mid-pack “chaos”.
