Coach Thomas Tuchel praised his Chelsea players for suffocating Atletico Madrid with relentless pressing as they beat the Spanish side 1-0 in Bucharest in the first leg of their last-16 Champions League tie.
Olivier Giroud's stunning overhead kick in the second half handed Chelsea the advantage going into the second leg at Stamford Bridge on March 17 but Tuchel was most pleased with how his players implemented their game plan and deprived the La Liga leaders of space and the ball.
"We knew they were ready to suffer with eight people in the box ... We never let them breathe or come out for counter-attacks," Tuchel said.
"We wanted to dominate in the opponents' half, to never lose concentration, not to make any easy mistakes and always be aware of quick counter-attacks for all their quality. It was a very disciplined performance, a deserved shutout."
Tuchel has led Chelsea to six wins in eight games in all competitions since succeeding Frank Lampard in January but this was his most significant result. The performance showed the impact he has already had on the team.
The German said the players were following his methods well but they had to keep on practising their new-found style of play.
"It's like learning a new song, you have to repeat it and repeat it so it gets more fluid and more in the rhythm," he said.
"Today was one of the toughest challenges to open up a defense like Atletico but we can and we will not stop pushing the guys to improve and keep going."
Tuchel also paid tribute to the professionalism of the 34-year-old Giroud, saying: "He trains like a 20-year-old. He is a guy who has a good mixture of serious and joy in training."
Atletico coach Simeone said he felt the game had been tight and did not agree that his side had been second best.
Elsewhere, Robert Lewandowski became the Champions League's third leading scorer of all time as holders Bayern Munich put one foot in the quarter-finals with a 4-1 thrashing of Lazio in Rome.
The Polish striker pounced on a poorly judged back pass after nine minutes to steer in his 72nd goal in the competition. In doing so, he surpassed former Real Madrid striker Raul in the competition scoring charts.
Only Juventus star Cristiano Ronaldo, with 134, and Barcelona's Lionel Messi, with 119, have scored more goals.