Women's Champions League: Chelsea Ladies 1-3 VfL Wolfsburg
Chelsea's hopes of reaching the Women's Champions League final diminished after they conceded three away goals in their first-leg defeat by Wolfsburg.
Fran Kirby fired a ball in for Ji So-yun to shoot across the keeper and give the hosts a second-minute lead.
Sara Bjork Gunnarsdottir headed an equaliser for Wolfsburg, who led when Maren Mjelde flicked in an own goal.
The German side stayed on top after the break and got a third with Lara Dickenmann's volley into the corner.
Emma Hayes' Chelsea must score at least three times in the second leg in Germany on 29 April to have any chance of reaching their first final in Europe's premier competition.
Wolfsburg, top of Germany's domestic league, looked shell-shocked after falling behind with the first meaningful attack of the tie as Chelsea's two creative forces Kirby and Ji linked up for the perfect start.
However the visitors picked themselves up, Dickenmann crossing for Iceland captain Gunnarsdottir to power past Hedvig Lindahl in front of a 3,329-crowd at Kingsmeadow.
Just a few minutes before half-time Mjelde was unfortunate to nod a Wolfsburg cross past her own keeper under pressure from Alexandra Popp, and Chelsea could not rebuild momentum.
Popp almost scored herself when Lindahl misjudged her whipped free-kick, which drifted wide, but the two-time winners went 3-1 up as Dickenmann acrobatically diverted a cross into the corner.
The WSL 1 leaders brought Eniola Aluko and Gemma Davison onto the field in search of a goal but failed to create any significant chances in response.
This is the first season in which two English clubs have reached the semi-finals of the Women's Champions League, with Chelsea and Manchester City bidding to become the first English side to reach the final of Europe's premier competition since Arsenal did so in 2007.
City drew 0-0 with French side Lyon earlier on Sunday.
Chelsea: Lindahl, Bright, Mjelde, Flaherty (Rafferty 75), Blundell, Chapman, Ji, Eriksson, Spence (Aluko 68), Cuthbert (Davison 84), Kirby.
Substitutes: Telford, Rafferty, Cooper, Davison, Aluko.
Wolfsburg: Schult, Fischer, Gunnarsdottir, Blasse (Kerschowski 62), Popp, Maritz, Pajor, Dickenmann, Harder, Hansen (Jakabfi 77), Goessling.
Substitutes: Frohms, Jakabfi, Baunach, Wullaert, Stolze, Wedemeyer, Kerschowski.