The Brazilian says despite going into the break 2-1 down on aggregate to the Romanians in the Europa League, he knew his side would win after seeing his team-mates' reactions
Vlad Chiriches scored at the end of the first half to put the Blues' progression in doubt despite Juan Mata's goal after 33 minutes, but second-half strikes from John Terry and Fernando Torres sent Rafa Benitez's side through to the quarter-finals.
The Brazilian centre-back was proud that his side played "with heart" to progress in the competition, and insists they are ready for a gruelling run-in as a fixture pile-up looms.
"They scored a goal from a set piece in the last minute [of the half], but at half-time I looked in the eyes of my players and I could see they would score goals and win this game," he told reporters. "We showed that in the second half. The team did a great job, scored three goals and we're through to the next round.
"You need to play with the heart and take your chances to play in big games. Not too many players in the world have the privilege of playing for Chelsea.
"The first half was difficult, but Chelsea have a lot of quality and we showed that in the second half. We controlled Manchester United at Old Trafford and this shows the potential of the players who play for Chelsea."
The Champions League holders have played 52 games this season and will have to complete another 18 if they are to lift both the FA Cup and Europa League trophies, and while Luiz admits Chelsea's squad is on the small side, he is ready for the challenging schedule.
"Eighteen games - it's good, I'm 25 years old! I think sometimes if you have more players to change it's much easier to help the team rebuild itself," he continued. "Chelsea don't have too many players like other teams; we have 22, 23 players, others have 30, so this is difficult for the coach sometimes to play always with the same players.
"I'm 25, I want to play. Personally I want to be on the pitch. Sometimes I'm tired but when I'm on the bench or not in the team I'm not too tired. I love to play games - I don't like to train, sometimes it is boring. Physically every day I want to play games."
The Brazil international also expressed his joy for struggling striker Fernando Torres, whose second-half finish proved to be the vital goal of the tie despite also crashing a late penalty against the crossbar.
"I'm happy with the team, with Fernando, with everyone. It's not the first time he's scored. Tonight I'm happy with him - he does it in training. The team played together and this is the key.
"The guys train every day and we have many guys with the quality to hit the net [from a penalty]. [Torres] had confidence with the game [to take it] and I respect that."