Sauber said Perez had a cold and a decision would be made on Friday with Mexican reserve Esteban Gutierrez, who has been tipped to move up to a race seat with the Formula One team next year, available as a stand-in.
Perez, 22, will replace Mercedes-bound Lewis Hamilton at McLaren next season.
Gutierrez is due to take part in a young driver test after next weekend's race in Abu Dhabi, which would be only his fourth outing for Sauber since 2009.
Like Perez, Gutierrez is backed by Telefonos de Mexico (Telmex), the telecoms provider run by Carlos Slim Domit, whose father is the world's richest man.
The Swiss-based team have had four podiums this year and are currently chasing Mercedes for fifth place in the constructors' championship.
Meanwhile, Sebastian Vettel will not relax his approach to the final races of the season despite having taken the lead in the championship.
Vettel now leads Alonso by six points but despite this momentum, the Red Bull driver insists there is no room for complacency.
"It's a better position to be in compared to the position we had three or four races ago," said Vettel ahead of the Indian Grand Prix. "We'll try to do our best in the next couple of races to make sure that we stay there, but in terms of our approach nothing really changes.
"They will be extremely important races for us. We have to try to do our best and then go from there."
The double world champion says being the hunted instead of the hunter is not something that will weigh heavily on his mind once the races get under way.
"I'm not thinking too much when I'm on the grid waiting for the lights to go," he said.
"It doesn't matter, to a certain degree, which position you are in the championship. It's something that you have in your head and you know, but I think the most important thing is to get off the line, have a good start, have a good race.
"If you are in a position where you have to score more points, you have to ensure that you finish ahead of ideally everyone or the one that you are after. If you are in the other position, you might afford here and there to not take the risks.
"We are in a good position but we are not in a position to sit back. That's why I remain focused and we will push as hard as we can to make sure that we stay where we are.
"That's the challenge that we have. As soon as we start to think too much, it's not good."
The Red Bull driver, who could become the youngest ever three-time champion this year, believes having already won titles will help him cope with the pressure in the remaining races.
"I think it helps. Winning the first championship was a big relief. My ultimate target was always to win the world championship and having done that was a great feeling.
"You have to have the approach that it all starts from zero again and you don't have an advantage just because you've won the last race, or you won the last championship but for me I felt I have done that, I have proven to myself that I'm good enough to do that.
"It helps to have more and more races, but it doesn't mean that you will never make a mistake again. We still have to make mistakes, I've made mistakes this year, but the most important thing is I don't do them more than once!
"There is always room for improvement no matter how many races you have but it surely helps to have a certain amount of experience."
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