Di Matteo said: "We are very frustrated, we walked into the dressing room and it doesn't really feel like a draw, more like a defeat. There is always a first time in life for things and I think we are going to train for 100 minutes now.
"It was an exceptional goal, the keeper couldn't get to it and we had a player on the line but it was well taken.
"I think we played extremely well, created many chances against the best defence in the league and maybe should have scored one more goal as we had so many chances. Let's not forget we are a newly-promoted team in this league and the players have done really well so far this season and we will just keep on going."
Leciester keep their 12 point lead ahead of the MK Dons.