Chelsea boss Jose Mourinho was bitterly disappointed with the scoreline after his side suffered their first Champions League defeat of the season.
The Blues have struggled for consistency this season and they were again on the losing side as they suffered a 2-1 away defeat at the hands of Porto.
They face Dynamo Kiev on October 20 next.
"It was a good performance with two ridiculous mistakes," Mourinho told reporters.
"Sometimes you make those mistakes and you are not punished, we were punished. With the second goal it's a ridiculous mistake.
"We watched dozens of repetitions of Porto taking corners, I thought we were completely ready for that and at a moment when the game was under control and we were preparing to make a change we conceded that goal.
"We had another similar mistake when they hit the post. Apart from that I thought we had balance, defensively we had no problems and the defenders played well.
'The basic thing in football is a defensive set play; the ball is there, you know the movements, control the spaces. The players reacted in a positive way and the team played for a positive result.
"Diego hit the bar, Ivanovic had a chance with an open goal and in the last minute it was a clear penalty [for a challenge on Kenedy]. We reacted and we reacted well.
"I don't think my players deserve me to be critical of them apart from the two mistakes but obviously I'm not going to point the finger.
"It's a difficult opponent and a difficult place to play. The Champions League brings a different emotion to matches, to the crowd and opposing players. I think the team played well.
"When the team is not winning on a regular basis it's normal you have to make changes. Games like tonight are the difficult ones to analyse and make decisions after because the result doesn't mean you played badly, the mistakes we made twice doesn't mean the team defended badly.
"When it's a disaster it's easier to make decisions. We have to find balance.
"We now have to home games in the Premier League and we need to try to get good results. Good feelings, happiness, self-esteem, the players need those to play and when luck goes against you it's difficult to have those feelings."