Thomas Tuchel believed Chelsea 'got lucky' to a degree despite cruising into the EFL Cup final.
Antonio Rudiger scored the only goal of the game, but Tuchel thought they rode their luck at times.
"We lost a bit of control, focus, some important duels and were lucky that suddenly we didn't concede," the German said.
"We were a bit sloppy and weren't fully aware of the danger. I had the feeling on the touchline we were playing with fire.
"Second half again, strong start for 15 minutes but again the same story. We conceded a penalty that wasn't a penalty or a big chance. We struggled to cope with the momentum.
"We had many ball losses, lost many challenges one-on-one. So big space to improve, it wasn't a super bad game, but it was an OK game and there were some moments and minutes that were good. But there are some that need huge improvement.
"We have to do better but performance-wise over the two matches, we deserved to win. For today, there is a lot to improve."
Tuchel has already won the FA Cup and Champions League with Chelsea despite being in charge for just over a year, and he now wants to add the League Cup to that collection.
He said: "When you go to the semi-final, of course, everybody wants to get to the final. We are very happy because Wembley is waiting, full house, cup final, this is where you want to be as footballers and coaches.
"This was the target and now we are there. Hard work and two good matches were needed and we did the job."