Jose Mourinho bemoaned Chelsea's complacency and the officials after his side were made to wait to secure qualification from Champions League Group G following a 1-1 draw at minnows Maribor. Nemanja Matic's close-range strike salvaged a draw for Chelsea after Agim Ibraimi's goal for Maribor, who were beaten 6-0 at Stamford Bridge two weeks ago.
Eden Hazard had a late penalty saved - but Mourinho felt Chelsea should already have been in front by then - only for substitute Diego Costa to have a strike ruled out for offside.
"Many times surprises happen when people are not fully focused, when they believe the game can't be a difficult one," Mourinho said.
"Only when Maribor scored did the players realise the game was in danger. After that, a fantastic reaction. We deserved to win, clearly.
"We scored two goals, two very good goals. The second goal, the referee (Italian Daniele Orsato) decided to disallow but it's a clear goal.
"Normally we should win because we scored two goals. But we have to accept it.
"We didn't reach the number of goals that we should have in the second half, but the team played well. And we scored a great second goal.
"And the referee's team did not have a good night."
Mourinho admitted his side paid the price for a lacklustre first half.
The Blues could have increased their advantage at the top of Group G to five points with two games to play had they won in the Slovenian city but they fell behind when Ibraimi curled into the top corner after 50 minutes.
Matic equalised after 73 minutes and although the Blues dominated in the final half hour, they were thwarted by the excellent Maribor goalkeeper Jasmin Handanovic, who made several brilliant saves including keeping out Hazard's late penalty.
Yet despite finishing strongly, it was an opening half performance which disappointed Mourinho.
"The first half we were poor, in the second half after their goal we played very well and normally we should win the game but when you don't play well for 90 minutes you risk," he said.
"In the last 30 minutes when we played really well, intense and creative and had a big desire to win we had lots of chances to do it, their goalkeeper was magnificent."
The Portuguese reacted to a forgettable opening 45 minutes by making a double change at half-time, bringing on Costa and Oscar for Andre Schurrle and Willian.
"I wasn't happy with the team and I was not happy with the performance. I changed at half-time with the conviction that the team was going to improve which I was proven right," Mourinho added.
"But they scored and when they scored their belief was higher."