Chelsea came away with a crucial victory over holders Lyon in the first leg of their Women's Champions League quarter-final in France.
Guro Reiten's brilliant curling finish put Chelsea 1-0 up in the first half after Scotland's Erin Cuthbert won the ball and skilfully teed her up.
Eight-time champions Lyon controlled most of the first half but were punished for missed opportunities.
Chelsea's Lauren James and Lyon's Delphine Cascarino both hit the post.
Having been knocked out by Lyon in the semi-finals in 2019, Chelsea arrived in France well aware of the difficult task facing them in their pursuit of a last four spot.
Lyon, who have progressed from 12 of their 13 quarter-finals, imposed their dominance early on, creating several chances for striker Eugenie Le Sommer which she could not convert.
Chelsea then demonstrated their ruthlessness in front of goal as Reiten's curling shot - their first on target - nestled in the far corner, before James rattled the post shortly afterwards.
The game opened up in the second half as Lyon pushed for an equaliser and Cascarino almost provided it when she struck the woodwork but Chelsea still posed a threat on the counter-attack.
Emma Hayes' side have the advantage in the second leg at Stamford Bridge next Thursday but there will be concern for key England centre-back Millie Bright, who went off injured before half-time and will have a scan on Thursday morning.
Moments of quality decide tight encounter
Lauren James has been a standout performer for Chelsea in the Women's Super League this seasonIt was only the fourth time this season the European champions had failed to find the back of the net and Chelsea will be encouraged by their solid defensive display in the second half.
They limited chances and frustrated Lyon, having picked them off against the run of play in the first half to take a slender lead back to London.
"It will give the team a lot of confidence. We looked nervous in the first 15 minutes. I could see a lack of movement but once we settled, we grew into the game and got more confidence," said Hayes.
"The result and keeping a clean sheet will give the team [confidence]. We have massive respect for Lyon. To win 1-0, I'm satisfied, but we know it's only half-time so there's things to improve on."
England international James showed her quality when she powerfully struck the post and set up Sam Kerr for a glorious chance later on - the Australian was flagged offside when she fired over the bar but replays showed she was onside.
However, it was Cuthbert's endeavour to win the ball back which led to Chelsea's crucial winner and she nutmegged Damaris Egurrola before laying it off perfectly for Reiten.
The game was decided by a few moments of quality, which Lyon often produce in their favour, and Chelsea still have a job on their hands to progress - but this is a huge result in their European history.
"I don't want to underestimate how hard it is to come here in a quarter-final. It's intimidating and I think we managed that really well," added Hayes.
"Pressure situations are moments that reveal your character, your wisdom, knowledge and experience. I felt the team delivered those characteristics under pressure.
"If you build consistency in your habits then every day is a Champions League day. We have become accustomed to the competition and we played with a wise head tonight."
Lyon, who suffered a shocking 5-1 defeat against Arsenal in October, could be boosted by the return of star striker Ada Hegerberg for the second leg as she was an unused substitute in France following her return from a lengthy injury.
Line-ups
Lyon Féminines
Formation 4-3-1-2
1Endler
12Carpenter21Gilles3Renard5Morroni
26Horan11Egurrola8Däbritz
10Marozsán
20Cascarino9Le Sommer
1Endler12Carpenter21Gilles3Renard5MorroniSubstituted forBachaat 55'minutes26Horan11Egurrola8DäbritzSubstituted forMajriat 69'minutes10MarozsánSubstituted forvan de Donkat 55'minutes20CascarinoSubstituted forMalardat 69'minutes9Le SommerSubstituted forBechoat 45'minutesSubstitutes
4Bacha7Majri14Hegerberg17van de Donk18Sombath23Cayman24Bruun25Benyahia27Becho28Malard50BelhadjChelsea Women
Formation 4-2-3-1
30Berger
15Périsset26Buchanan4Bright7Carter
8Leupolz5Ingle
10James22Cuthbert11Reiten
20Kerr
30Berger15PérissetSubstituted forMjeldeat 85'minutes26Buchanan4BrightSubstituted forErikssonat 44'minutes7Carter8Leupolz5IngleBooked at 54mins10JamesSubstituted forRytting Kanerydat 85'minutes22CuthbertBooked at 57minsSubstituted forCharlesat 71'minutes11Reiten20KerrSubstitutes
1Musovic16Eriksson17Fleming18Mjelde19Rytting Kaneryd21Charles27Abdullina28Cankovic32OrmanLive Text
Match ends, Lyon Féminines 0, Chelsea Women 1.
Second Half ends, Lyon Féminines 0, Chelsea Women 1.
Attempt missed. Wendie Renard (Lyon Féminines) header from the centre of the box is close, but misses to the right. Assisted by Selma Bacha with a cross following a corner.
Corner, Lyon Féminines. Conceded by Maren Mjelde.
Offside, Chelsea Women. Sam Kerr tries a through ball, but Guro Reiten is caught offside.
Attempt saved. Guro Reiten (Chelsea Women) left footed shot from more than 40 yards on the left wing is saved in the top left corner.
Attempt saved. Johanna Rytting Kaneryd (Chelsea Women) right footed shot from the right side of the box is saved in the top centre of the goal. Assisted by Guro Reiten.
Offside, Lyon Féminines. Selma Bacha tries a through ball, but Vicki Becho is caught offside.
Substitution, Chelsea Women. Maren Mjelde replaces Ève Périsset.
Substitution, Chelsea Women. Johanna Rytting Kaneryd replaces Lauren James.
Corner, Lyon Féminines. Conceded by Magdalena Eriksson.
Attempt missed. Amel Majri (Lyon Féminines) left footed shot from a difficult angle on the left misses to the left. Assisted by Selma Bacha with a cross following a corner.
Corner, Lyon Féminines. Conceded by Ève Périsset.
Attempt blocked. Daniëlle van de Donk (Lyon Féminines) right footed shot from the centre of the box is blocked. Assisted by Amel Majri.
Offside, Lyon Féminines. Damaris Egurrola tries a through ball, but Melvine Malard is caught offside.
Lauren James (Chelsea Women) wins a free kick in the defensive half.
Foul by Selma Bacha (Lyon Féminines).
Melanie Leupolz (Chelsea Women) wins a free kick in the defensive half.
Foul by Vicki Becho (Lyon Féminines).
Attempt missed. Sam Kerr (Chelsea Women) left footed shot from the left side of the box is close, but misses to the left. Assisted by Lauren James with a through ball.