"Nothing is impossible, because this is sport," he told the Spanish press.
"But it would be a strange thing tomorrow if we went out and won the race," he added. "The first thing I would do is rub my eyes."
Even Red Bull, whose two drivers managed to split the Mercedes cars in Saturday's Chinese rain, is not very hopeful.
Asked if his Red Bull can compete with the powerful Mercedes, Sebastian Vettel answered: "Well, I think if we put two chicanes in all the straights, then yes."
More than a second slower than pole-sitter teammate Lewis Hamilton on Saturday, Mercedes teammate Nico Rosberg blamed his fourth place on his faulty dashboard display.
"I was half a second quicker going into the last corner," said the German, "but my time delta on my steering wheel display said that I was two tenths slower. So I just took a big risk and spun."
Mercedes chief Toto Wolff, however, said Hamilton's six-tenths advantage over second place showed that the 2008 world champion "was in a league of his own" on Saturday.
Indeed, Hamilton drove past F1 legends Jim Clark and Alain Prost's career pole tallies in China, and on Sunday the Briton could complete a rare hat-trick of race wins.
"What is most striking is the gap between him and the others," former driver Patrick Tambay told France's RMC.
"It shows that it is probably the man, the driver, that is making the difference," he added.