The Blues go into the match at Stamford Bridge trailing 3-1 from the first leg in Naples three weeks ago, and now without a permanent manager as Andre Villas-Boas has been sacked and replaced by caretaker Roberto Di Matteo since that match.
Their hopes of advancing to the quarter-finals have been widely written off as they would need to become only the fourth club to overturn a first-leg deficit of two goals or more in the Champions League.
However, Terry still believes his side have a chance.
"If it all goes well, it could go down as one of the great nights of Chelsea's history," he said.
History is well and truly against
Terry said: "It'll be very tough. Seeing their last game, too, when they won 6-3, defensively, we need to be really solid.
"It'll be a balance, and communication will be key. They'll have watched videos of us and know we can open teams up.
"We can break teams down and be solid ourselves. But an early goal and a good start would be great for us."
While they may hold all the aces, Napoli have arrived in London determined not to fall into the trap of over-confidence, having watched Arsenal almost overturn AC Milan's 4-0 first-leg advantage last week.
"It's important we don't do anything different to what we usually do," coach Walter Mazzarri said.
"If we changed the way we played, that would be a risk.
"But I don't think my team can underestimate the importance of a game like this."
He added: "When we don't have the ball, we must be like 11 lions, attacking them constantly to get it back. When we have the ball, we must do everything we can to put them under pressure."
Star striker Edinson Cavani, who scored a controversial goal in the first leg, said: "We know what to expect and what they can do.
"It'll be a tough match and a very difficult match for us.
"We saw in the Arsenal against Milan match that a team full of champions can change a tie in a few minutes."
Chelsea were abject defensively in Naples but caretaker manager Roberto Di Matteo has revitalised them in the past week and a half.
Mazzarri said: "The fact they've won two out of two since Di Matteo was in charge is a big morale boost for their team. That worries me.
"But I'm confident that, if we play the match we're capable of, we'll have nothing to fear."
Napoli also enjoyed a boost on Tuesday when Mazzarri was given the green light to sit on the bench after the Court of Arbitration for Sport agreed to study an appeal by the club into their manager's two-match touchline ban.