PSG lead Chelsea 3-1 heading into Tuesday's quarter-final second leg in London, while Eto'o has not played in three games due to a hamstring injury sustained in his team's 6-0 demolition of Arsenal.
Chelsea have lost two of the three games Eto'o has missed but manager Jose Mourinho claimed he will not risk the Cameroonian striker against PSG if the 33-year-old fails to complete a full training session with the main squad.
Eto'o did not join his team-mates in a light training session on Sunday.
"Will Eto'o be fit? Let's see. Let's see if he trains on Monday," Mourinho said after training.
"Maybe he could play but to risk a player you need to have minimum conditions to take that risk.
"If you think he's going to be out after 10 minutes of the game you can't take that risk. If there is a minimum of risk, then yes.
"We need to score goals. If we don't score a minimum of two goals we are out. We know that, so if we can have everybody available who can give us a chance to score goals then let's do that."
Eto'o is Chelsea's equal-leading goal-scorer in the Champions League this season with three, alongside Fernando Torres, while the former Barcelona, Inter and Anzhi Makhachkala striker has 11 goals to his name in all competitions, behind only Eden Hazard (17) and level with Oscar.
All 11 goals have come at Stamford Bridge this season, which would make Eto'o the prime candidate to start up front for Chelsea on Tuesday.
But despite a two-goal deficit and an injury to his leading central striker, Mourinho denied he was worried.
"Am I nervous about the match? No," the Portuguese manager said.
"I'd have been nervous if we'd won 1-0 or 2-0 in Paris, but losing 3-1 means I am not nervous. I want to enjoy the game, I want to enjoy the fight, I want to enjoy the risk. So, no nerves.
"A big game, an almost impossible job - so let's go.
"What's important is that they give everything, that they leave nothing on the field. PSG as a club don't have the experience we do."
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