Leicester City manager Claudio Ranieri lamented conceding just before half-time in his side's loss to Chelsea in the EFL Cup.
A Shinji Okazaki brace, after poor defending by the visitors, had put Leicester on track at the King Power Stadium on Tuesday.
But Gary Cahill scored from a corner just prior to the break, before Cesar Azpilicueta's stunning volley led to the equaliser and Cesc Fabregas was the hero in extra time.
Ranieri rued the goal just before half-time as the decisive moment in his side's loss.
"I think the key was when we conceded a goal from the last corner of the first half," he said, via the club's website.
"We lost two dangerous men, [David] Luiz on the first post and Gary Cahill at the back post.
"From that point something changed because I put so many new players and they don't have 90 minutes."
Making things even more difficult for Leicester was the sending off of Marcin Wasilewski just before the end of regulation time.
Ranieri said his hope was that his side could hold on for penalties, before Fabregas' heroics.
"The second key was when Wasilewski was sent off. At that point they scored again and it was difficult for us," he said.
"I hoped to keep it to 2-2 in extra time until the end. I told the players to stay together and close the space. But Fabregas scored twice again and it was very difficult for us."
Leicester must now regroup before a trip to Old Trafford to face Manchester United in the Premier League on Saturday.