Gary Cahill admits the 3-3 draw with Manchester United felt like a defeat after Chelsea squandered a 3-0 lead.
Cahill made his debut for the Blues after arriving from Bolton and put in a solid display alongside David Luiz in central defence but was disappointed not to win the game.
The defender says Chelsea should have been able to see the game out but has again pointed to the penalty decisions as the turning point.
"It was a fantastic game to be involved in and it was in at the deep end but these are the games you want to be involved in, however any game you go 3-0 up you expect to win so that has put a dampener on my debut," Cahill revealed.
"It is a sickening feeling like we have lost the game. The mood is a bit flat and we are disappointed.
"The second half we started fantastically well and went 3-0 up and really should have seen the game off from there, but the second penalty was disappointing.
"The first one was probably a penalty but the second one was right in front of me and I didn't think it was a penalty at the time and seeing the replay I haven't changed my mind, so that went against us at a crucial part of the game."