Chelsea slumped to their first pre-season defeat on Sunday as they were beaten 3-0 by Werder Bremen in Germany to spoil the return of Didier Drogba and the debut of goalkeeper Thibaut Courtois.
Ivory Coast legend Drogba made his first appearance for Chelsea since scoring the penalty that won the 2012 Champions League in Munich when he came on as a second-half substitute for summer signing Diego Costa.
However, Jose Mourinho's side were already 2-0 down at that point and Drogba's return ended in a tame defeat at the Weserstadion.
"They are the best team we've faced in this period," said Mourinho. "We knew they were in a more advanced stage of pre-season so we were expecting a competitive, intense game."
Blues captain John Terry conceded a soft penalty after 20 minutes when he needlessly blocked the ball with his arm and Dutch winger Eljero Elia stepped up to plant his spot-kick past Belgian 'keeper Courtois, who has joined up with Chelsea after a long-term loan at Atletico Madrid.
It got worse for the visitors 17 minutes later when Terry was again implicated as Polish winger Ludovic Obraniak darted past the static centre-half to glance a header past Courtois.
"We came here and the referee thought it was a circus for Bremen fans to have fun and he killed the match," Mourinho told the Chelsea website.
"I like their team, they are fast, defend with a lot of players, they are physical. It was the perfect opponent but we didn't play."
Mourinho made several changes at the break, including the introductions of Drogba and Branislav Ivanovic, while Eden Hazard entered the fray in the second half.
Bremen won a second penalty in the last minute when Dutch defender Nathan Ake was punished for what appeared to be a fair challenge but it didn't matter to Felix Kroos, who stroked the ball past substitute 'keeper Petr Cech from 12 yards.
"Every duel and free-kick went against us, the penalties, especially the last one, were nonsense. Being aggressive with Ake, an 18-year-old, was disappointing. We wanted to train but the referee didn't let us have a good session," added the coach.
The Portuguese also said many of his players including Courtois are well short of match fitness and preparation following the World Cup.
"Courtois is the same as the others, two days training and playing today for 45 minutes, he needs to play, we don't have lots of time. It's only two weeks until the start of the season so we gave him and Petr (Cech) 45 minutes each.
"He made a fantastic save from Di Santo, with the other goal he had no chance, but that save was fantastic."
Chelsea, who had previously registered four wins and a draw in pre-season, continue their preparations with a game against Hungarian side Ferencvaros next Sunday.
Their opening Premier League game will be away to promoted Burnley on Monday, August 18.