Meanwhile, in the other semi-final, it's half-time in the first leg between Bayern Munich and Barcelona and it's goalless.
FT: Lyon 2-1 Chelsea
Erin Cuthbert's second-half half-volley has given Chelsea hope for next Sunday's second leg, after a more dominant first half from the holders.
FULL-TIME
Lyon 2-1 Chelsea
The whistle goes for a push in the box and that Lyon corner comes to nothing.
The first leg of this semi-final ends and Chelsea will take an away goal back to Kingsmeadow.
Post update
Lyon 2-1 Chelsea
Lyon have forced a corner and it'll surely be this game's final act.
SUBSTITUTION (Chelsea)
Lyon 2-1 Chelsea
South Korea's Ji So-Yun is replaced by Drew Spence in midfield for Chelsea, with the game almost over. There are around 80 seconds left.
Post update
Lyon 2-1 Chelsea
Pat Nevin
Former Chelsea and Scotland winger on BBC Sport
"The players must be exhausted, the effort they have put into the game has been incredible."
Post update
Lyon 2-1 Chelsea
Chelsea keeper Ann-Katrin Berger does well to punch away Griedge M'Bock Bathy's header, as three minutes of added time are signalled.
Post update
Lyon 2-1 Chelsea
Both sides are maybe starting to tire a little. It's been an intense first leg.
Post update
Lyon 2-1 Chelsea
ReutersCopyright: Reuters
There are just a few minutes of normal time remaining in this first leg and I wonder if some Chelsea fans would take this scoreline now, with a home leg to come.
SUBSTITUTION (Lyon)
Lyon 2-1 Chelsea
Delphine Cascarino gets a rest after a cracking performance for the hosts, and on comes Amel Majri in midfield for Lyon.
CLOSE!
Lyon 2-1 Chelsea
Beth England shoots low and just wide for Chelsea, from inside the D.
The visitors have looked good in the past 15 minutes or so.
SUBSTITUTION (Lyon)
Lyon 2-1 Chelsea
Wales legend Jess Fishlock comes off, as versatile Japan star Saki Kumagai comes on.
SUBSTITUTION (Chelsea)
Lyon 2-1 Chelsea
Finland's Adelina Engman comes on for Chelsea, as Ramona Bachmann goes off.
Post update
Lyon 2-1 Chelsea
Erin Cuthbert tries to burst through the Lyon defence as she looks for a second, but Lucy Bronze gets a strong foot in to deny her.
'Fabulous goal' from Cuthbert
Lyon 2-1 Chelsea
Pat Nevin
Former Chelsea and Scotland winger on BBC Sport
"The technical ability there - it bounced just in front of the goalkeeper, but that's a fabulous goal. We've got a game on."
Post update
Lyon 2-1 Chelsea
ReutersCopyright: Reuters
It really was a terrific effort from Chelsea's Erin Cuthbert.
Moments later, Selma Bacha's powerful shot for the hosts from range is held by Ann-Katrin Berger.
GOAL: Lyon 2-1 Chelsea
Erin Cuthbert
Fantastic goal! Chelsea substitute Beth England nods the ball down for Scotland's Erin Cuthbert, who sends a first-time, half-volley straight in to the bottom corner from outside the area.
It's a quality strike and a massive moment in this semi-final. Chelsea have an away goal.
Post update
Lyon 2-0 Chelsea
One of those 'Viking Thunderclaps' - made famous by Iceland fans at men's Euro 2016 - is roaring around the stadium as the home fans enjoy themselves, with their side in control of this tie.
Live Reporting
Tom Garry
All times stated are UK


ReutersCopyright: Reuters 

ReutersCopyright: Reuters
Latest PostFT: Lyon 2-1 Chelsea
An encouraging fight back from Chelsea in Lyon means the Blues have hope of reaching the Women's Champions League final in Budapest on 18 May.
A 1-0 win or better at Kingsmeadow next Sunday would be enough to send Emma Hayes' side through to their first European final.
I hope you can join us again for that. Until then, good bye!
Result in the Women's Super League
FT: West Ham 1-2 Birmingham City
Earlier this afternoon, Birmingham City hit back to win away at 10-player West Ham in the WSL.
You can read our match report on that game here.
Elsewhere in the Women's Champions League
HT: Bayern Munich 0-0 Barcelona
Meanwhile, in the other semi-final, it's half-time in the first leg between Bayern Munich and Barcelona and it's goalless.
FT: Lyon 2-1 Chelsea
Erin Cuthbert's second-half half-volley has given Chelsea hope for next Sunday's second leg, after a more dominant first half from the holders.
FULL-TIME
Lyon 2-1 Chelsea
The whistle goes for a push in the box and that Lyon corner comes to nothing.
The first leg of this semi-final ends and Chelsea will take an away goal back to Kingsmeadow.
Post update
Lyon 2-1 Chelsea
Lyon have forced a corner and it'll surely be this game's final act.
SUBSTITUTION (Chelsea)
Lyon 2-1 Chelsea
South Korea's Ji So-Yun is replaced by Drew Spence in midfield for Chelsea, with the game almost over. There are around 80 seconds left.
Post update
Lyon 2-1 Chelsea
Pat Nevin
Former Chelsea and Scotland winger on BBC Sport
"The players must be exhausted, the effort they have put into the game has been incredible."
Post update
Lyon 2-1 Chelsea
Chelsea keeper Ann-Katrin Berger does well to punch away Griedge M'Bock Bathy's header, as three minutes of added time are signalled.
Post update
Lyon 2-1 Chelsea
Both sides are maybe starting to tire a little. It's been an intense first leg.
Post update
Lyon 2-1 Chelsea
There are just a few minutes of normal time remaining in this first leg and I wonder if some Chelsea fans would take this scoreline now, with a home leg to come.
SUBSTITUTION (Lyon)
Lyon 2-1 Chelsea
Delphine Cascarino gets a rest after a cracking performance for the hosts, and on comes Amel Majri in midfield for Lyon.
CLOSE!
Lyon 2-1 Chelsea
Beth England shoots low and just wide for Chelsea, from inside the D.
The visitors have looked good in the past 15 minutes or so.
SUBSTITUTION (Lyon)
Lyon 2-1 Chelsea
Wales legend Jess Fishlock comes off, as versatile Japan star Saki Kumagai comes on.
SUBSTITUTION (Chelsea)
Lyon 2-1 Chelsea
Finland's Adelina Engman comes on for Chelsea, as Ramona Bachmann goes off.
Post update
Lyon 2-1 Chelsea
Erin Cuthbert tries to burst through the Lyon defence as she looks for a second, but Lucy Bronze gets a strong foot in to deny her.
'Fabulous goal' from Cuthbert
Lyon 2-1 Chelsea
Pat Nevin
Former Chelsea and Scotland winger on BBC Sport
"The technical ability there - it bounced just in front of the goalkeeper, but that's a fabulous goal. We've got a game on."
Post update
Lyon 2-1 Chelsea
It really was a terrific effort from Chelsea's Erin Cuthbert.
Moments later, Selma Bacha's powerful shot for the hosts from range is held by Ann-Katrin Berger.
GOAL: Lyon 2-1 Chelsea
Erin Cuthbert
Fantastic goal! Chelsea substitute Beth England nods the ball down for Scotland's Erin Cuthbert, who sends a first-time, half-volley straight in to the bottom corner from outside the area.
It's a quality strike and a massive moment in this semi-final. Chelsea have an away goal.
Post update
Lyon 2-0 Chelsea
One of those 'Viking Thunderclaps' - made famous by Iceland fans at men's Euro 2016 - is roaring around the stadium as the home fans enjoy themselves, with their side in control of this tie.