Head coach Thomas Tuchel has claimed that he used the wrong tactics despite witnessing Chelsea progress through to the Champions League quarter-finals with a 2-1 victory over Lille.
The European champions came from behind to progress 4-1 on aggregate, moving a step closer to defending the trophy that they won at the end of last season.
However, Tuchel was quick to acknowledge that the Blues had under-performed during the first half, the German suggesting that it was a consequence of using Jorginho, Mateo Kovacic and N'Golo Kante in a midfield three.
Speaking to BT Sport, Tuchel said: "The quarter-finals is a big step. We showed resilience and mentality to overcome difficulties. We did what was necessary. We dug in and got a deserved win. It's difficult here.
"We weren't so good in the first half. The pitch was horrible and it made things complicated. It was a new pitch not ready to play on. The tactics weren't right in the first 20 minutes, I take responsibility. Then it was more fluid. It was very important to calm everyone down. We were lucky with the post.
"We hope and expect to carry on. We want to compete. It took a lot of sacrifice, we fought hard to be in the last eight. We're excited for the draw. We have a game in Middlesbrough three days later."
Chelsea will discover their opponents for the quarter-finals when the draw is made on Friday morning.
