Claudio Ranieri was disappointed after Leicester drew with Aston Villa and blew their chance to go further clear at the top of the Barclays Premier League.
The Foxes lead the table by a point following Saturday's 1-1 draw in Birmingham, where Shinji Okazaki's fifth goal of the season put the visitors ahead.
Mark Bunn kept Villa within touching distance by saving Riyad Mahrez's first-half penalty, allowing Rudy Gestede to cash in with 15 minutes left.
The substitute's deflected effort beat Kasper Schmeichel and left Ranieri frustrated after missing the chance to move three points clear.
"Yes, we lost two points," he said. "We started very well and scored a goal but after the missed penalty the Aston Villa players took a new energy. If we score a second goal, we close the match.
"We are very sad but also I say to the players 'if we make the performance the result is not important'. The performance was good because we played well in the first half.
"It's one point, it's okay, it's a derby - but we are disappointed."
Things could have been so different had Mahrez not missed a second successive penalty, but Ranieri refused to say whether the winger would lose spot-kick duties.
"Now is not important if I change the penalty man," the Italian said. "I'll speak with him and then I'll choose.
"From the bench it was difficult to see if it was handball but if it's a penalty it's a red card."
Leicester have won once in their last five league games as they try to keep their challenge on track.
Arsenal will overtake them on goal difference with a point at Stoke on Sunday, but Ranieri insists he would not watch their title rivals.
"Maybe I will go with my family to the restaurant," he said. "It's not important now for us. It's only January.
"If we stay at the top of the league (later in the season), I will also watch the other teams."
Villa are nine points from safety after collecting four points from their last two matches, but Remi Garde believes it could have been even better had Robert Huth been penalised for striking Libor Kozak in the face.
The Frenchman says it "definitely" should have been a second-half penalty and remains confident Villa's new-found belief can give them a shot of an unlikely escape.
"If you look at the two games we've played we can be pleased about the spirit," Garde said. "These players have the right attitude to try to save the club from relegation.
"Sometimes it takes time. If there is pre-season it's because it's useful and when you don't have pre-season to work with your team it's more difficult.
"I didn't have this time and when I arrived the team had lost seven games in a row. I know my face was new in the dressing room - my language as well - but it doesn't take hours to put it right."