Chelsea responded to their opening round defeat against Basle by winning at Steaua Bucharest and on Tuesday night face the first game of a potentially decisive double-header with group leaders Schalke, who have maximum points from their first two games.
The Chelsea captain said: "We had a minor blip at home (against Basle). Win this game and we're in a much stronger position.
"We're not coming here under false pretences that we're going to come here, pick up three points easily. We understand it's going to be a tough night."
Jose Mourinho knows the bouts with the Bundesliga's Royal Blues could be key, but is calm about Chelsea's position.
The Chelsea boss said: "We need points over these two matches. That's obvious.
"But we're in condition to play without thinking about finishing first or second.
"I don't think it's yet the time to have the calculator and to be counting the number of points you need to qualify."
The Veltins Arena contest is Chelsea's first in Germany since the 2012 Champions League final, when Terry lifted the European Cup following the penalty shootout defeat of Bayern Munich, despite being suspended for the final.
It is also the teams' first meeting since November 2007, shortly after the abrupt end of Mourinho's first spell in charge, at the beginning of a season which ended in a Champions League final shootout loss to Manchester United.
In Moscow it was Terry who missed the decisive kick and he is eager to experience a European Cup win on the field.
"I played in one (final) and was very disappointed in the one in Moscow, but delighted for the side to go on and win it the way we did," Terry said.
"But as an individual you want to be playing in those games, in those moments and that's what I'm aiming to do."
This season could provide his last opportunity to do so at Chelsea, with his contract expiring at the end of the campaign.
Terry steered clear of the subject of his future.
"The manager was honest with me at the start of the season and said 'listen, if you play well and stay fit, you'll be in the side'," he added.
"If that's not the case, I won't be in the side, which then puts everything else up in the air.
"I'm just concentrating on playing well, which I feel as if I'm doing at the moment.
"Hopefully everything else takes care of itself."
Chelsea are without Ashley Cole (ribs), but Andre Schurrle (leg) could return.
Terry could be partnered by Gary Cahill in defence, with David Luiz making way following an error-strewn display against Cardiff.