Lucy Bronze had not tasted defeat as a Chelsea player before Wednesdays game against Manchester City
Defender Lucy Bronze says Chelsea were "miles off" their best as they suffered their first defeat under manager Sonia Bompastor after 28 games.
Wednesdays 2-0 Womens Champions League quarter-final first-leg loss at Manchester City also ended a 31-match unbeaten run - since Liverpool beat them 4-3 in the Womens Super League last May.
Had they avoided defeat, Chelsea would have set a new record for the longest ever unbeaten streak by a WSL team across all competitions.
"I dont think we were good enough," said Bronze after the game against her former club. "We didnt have enough effort in our press. We were really sloppy on our passing.
"We were miles off our game, Sonia [Bompastor] said that at half-time. It improved a little bit in the second half, but thats when they got their goals."
The match was the second instalment of four successive games between Chelsea and City, with Bompastors side having won won Saturdays womens League Cup final 2-1.
They visit City again in the WSL on Sunday, before the Champions League return at Stamford Bridge on Thursday.
Bompastor will look for an immediate response, and her Blues have not shied away from sharing their Champions League title aspirations and will not want to fall short at this stage.
The 33-year-old Bronze, who has won the European trophy five times in spells at Lyon and Barcelona, added: "Thats what football is - you have ups and downs. We have had a fantastic first half of the season.
"Everyone ups their game when they play Chelsea now because they want to be the first team to beat us, and thats happened today. We just have to go back and be better for the weekend."
Sonia Bompastor went unbeaten in her first 28 games as Chelsea boss
Chelsea have been relentless this season and are the only team still undefeated in the WSL after the first 16 games.
Their impressive unbeaten record may have gone, but hopes of winning a historic quadruple are still alive and Bompastor believes her side still have what it takes to bounce back.
"We said our ambitions at the beginning of the season and we wont change that," she said. "Our ambitions are still there. That is the first time we have been beaten, so that is not a drama.
"Going unbeaten is a nice thing but its not a trophy so we dont care about that. I want us to win the right games – the important ones – and win as many trophies as we can."
Chelsea learned the hard way last season that Champions League first-leg victories cannot be taken for granted.
They beat Barcelona 1-0 at Stamford Bridge in the semi-final, before falling to a 2-0 defeat in the away return.
"Its only half-time," former Manchester City midfielder Izzy Christiansen told BBC Radio 5 Live. "We know Chelsea will find more gears. They have got so much quality. It is beautifully poised for Thursday night."
Chelsea are eight points clear of Arsenal and Manchester United at the top of the WSL and 12 above fourth-placed Manchester City.
While the two sides meet in the league on Sunday, former Manchester City forward Ellen White believes Chelseas focus should be on the Champions League tie instead.
"Chelsea just need to go to Stamford Bridge and that is the one they need to win the most," she told 5 Live.
"Ultimately they are quite far ahead in the league, but they want to win the Champions League so they have to go to Stamford Bridge and score a lot of goals."