The 35-year-old missed Tuesday's 2-1 Champions League last-16 loss at Paris St Germain with a hamstring complaint, which could yet keep him out of Sunday's FA Cup fifth-round tie with Manchester City.
Terry's next appearance will be his 700th for Chelsea, who maintain a contract offer might be forthcoming after the defender revealed he would be leaving Stamford Bridge when his deal expires at the end of the season.
With Kurt Zouma also absent due to a season-ending knee injury, Cahill partnered Branislav Ivanovic at centre-back and the pair performed well, despite PSG ending the Blues' 12-match unbeaten run.
"I played with Iva in the Premier League and in the (2013 Europa League final) and was successful, so I don't see it being a problem if John's not available," Cahill said on espnfc.com.
"Ideally we would have everyone available, all our strongest players.
"Let's see with John. But I've played with Iva in big games before, so I don't see it being a problem."
Edinson Cavani earned PSG victory in the first leg at Parc des Princes as the teams met in the Champions League for a third straight season.
Away goals have proved the difference in the last two years - Chelsea won the quarter-final tie in 2014 and PSG advanced to the last eight 12 months ago - and John Obi Mikel hopes his strike can be decisive in the March 9 return leg at Stamford Bridge.
The midfielder's sixth goal in 358 Chelsea appearances cancelled out Zlatan Ibrahimovic's free-kick opener, which deflected off the Nigerian, before Cavani struck.
"I think it's going to prove a big goal," Mikel told Chelsea TV. "Hopefully the goal that puts us through in the tie.
"If we can get 1-0 back home, we're through. I think we're still alive."
Chelsea's away goal might have come sooner only for a Diego Costa header being well saved by goalkeeper Kevin Trapp.
"I think we deserved more, we deserved to get a draw or win the game," Mikel added.
"We came out here to play football and I think we've done that. I think we put in a very good performance.
"We defended when we had to and played when we had to. It was a very difficult game, but one we really did well in.
"We had Iva to play centre-back and Gaz (Cahill), who has not been playing for a while. They did fantastically well.
"First goal, big deflection from me. The second goal as well, I don't know...
"After the first goal we came back strong and got the equaliser."
Ivanovic reckons Chelsea must keep a clean sheet to advance.
"We all hope (Mikel's goal) is going to be massive for us," the Serbia defender said.
"(But) we have to concentrate. We know we have to play defensively a perfect game at home to go through."
Chelsea goalkeeper Thibaut Courtois made a number of fine saves before being beaten by Cavani and PSG may rue not adding to their tally.
Ibrahimovic is confident they will go through if they can repeat their display in London - sentiments echoed by midfielder Blaise Matuidi.
"We played really well," Matuidi told the club's official website.
"Perhaps we can regret not getting that third goal, but we are more disappointed with conceding that goal just before half-time.
"We won this first round, even if that Chelsea goal is a potential danger, but we know we are good enough to qualify."