Chelsea will have to come from behind against Barcelona to reach the Women's Champions League final after losing the first leg at Stamford Bridge.
Caroline Graham Hansen superbly curled in the winner in the first half for Barcelona, before the visitors lost England defender Lucy Bronze to injury.
The England right-back went down off the ball holding her knee in the 66th minute, a day after her national team captain Leah Williamson was ruled out of the World Cup with a serious knee injury.
Bronze's injury was the most significant moment of the second half that Barcelona dictated to see out a win that means Chelsea know they must score at least once when they travel to Spain on Thursday for the second leg.
The semi-final was a repeat of the 2021 final in which Barcelona put four goals past Chelsea after 36 minutes - and they threatened to do the same in London.
Graham Hansen was afforded too much space as she cut in off the right and fired brilliantly past goalkeeper Ann-Katrin Berger within four minutes.
Chelsea responded, creating chances of their own through Guro Reiten and Sam Kerr - but Barcelona substitute Marta Torrejon also struck the post late in the second half.
Emma Hayes' side, who are seeking to win the Treble this season, know they will need a strong performance in Spain to overcome last year's runners-up and keep that dream alive.
