Esteban Gutierrez is set to secure one of the four last race seats on the 2014 grid.
He was recently spotted visiting Caterham's UK headquarters, but Gutierrez staying at Sauber would firm up Giedo van der Garde's chances of remaining in green overalls next year, possibly to be joined by the Swedish rookie Marcus Ericsson.
The other remaining 2014 vacancy is at Marussia, but team boss John Booth said the Briton Max Chilton is likely to remain Jules Bianchi's teammate.
"We are very close (to re-signing) with Max, very close," he told Britain's Sky this week.
"He wants to stay and we want him to stay so it's a matter of sorting the details out really."
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