Guro Reiten, in the form of her life, scored the winner shortly before the half-hour, a pinpoint finish that owed much to the industry, skill and vision of Erin Cuthbert.

Though what proved the winner probably came somewhat against the run of play, the Blues were no doubt the better team thereafter. Lauren James crashed a shot against the post, Reiten hit the side-netting and Sam Kerr fired wide when through on goal, with Ann-Katrin Berger only making one save of note, tipping Delphine Cascarino’s shot onto the post.

We overcame the setback of losing Millie Bright to injury in the first half to produce a defensive masterclass, Kadeisha Buchanan in particular imperious on her return to the OL Stadium. But singling any player in blue out would be harsh, for this was a dynamic and determined collective effort against a team who have won six of the last seven Champions League crowns. It must surely go down as one of the club's greatest single results.

But the job is not done! The return leg at Stamford Bridge next Thursday 30 March promises to be a cracker and tickets, starting at just £9 for adults and £1 for juniors and seniors, are available now.

The selection

Emma Hayes made seven changes to the side that started the FA Cup win at Reading on the weekend.

Kerr and James returned having been rested for that one, and they were joined in attack by Reiten and the fit-again Cuthbert.

Melanie Leupolz supported Sophie Ingle in midfield, and there were also starts for Berger, Eve Perisset and Buchanan, all uninvolved at Reading.

Lyon begin the brighter

Hayes had predicted a cagey opening and that is what we got on a pleasant spring afternoon in France’s third-largest city until the contest burst into life in the ninth minute.

A long pass was cleverly flicked in Eugenie Le Sommer’s direction by Dzsenifer Marozsan. The striker, back in the Lyon side, bore down on goal and dinked the ball past Berger but also, thankfully, the near post.

The Blues struggled at times to retain possession in the face of Lyon’s press, but when we could we looked dangerous on the break. James broke from deep in trademark style and found Kerr, who wasn’t able to return the favour.

Guro at it again!

Midway through the half we dealt with a succession of Lyon corners well, Berger dominant amid crowded six-yard boxes. And then, with 28 minutes on the clock, we brilliantly took the lead.

Some Cuthbert magic in the middle of the park, including a delightful nutmeg, helped her bypass Lyon’s midfield and she had the vision to spot Reiten ahead of her in space. The pass that followed was begging to be hit and that is exactly what the Norwegian did, curling a right-footed shot beyond the reach of Christiane Endler and inside the far post.

We so nearly doubled our lead five minutes later. James drifted off the right flank and with barely any backlift whipped a left-footed 20-yard shot goalwards that crunched against the base of the upright and bounced out. It was a timely reminder, as if Lyon needed it, of James’ threat at any moment.

A dark moment for Bright

Dabritz had a long-range shot of her own that whistled wide, but otherwise Chelsea were largely comfortable until the break. The only disappointment was the withdrawal of our leading appearance-maker Bright because of a leg injury she just couldn’t shake off. Magda Eriksson was the natural replacement and took the armband from her long-time partner in central defence.

In fact, it was Chelsea who threatened last in the first half. Leupolz released Kerr, who had otherwise not had much service, and she half-volleyed wide from a narrowing angle.

We started the second period confidently, with both Kerr and James threatening Lyon’s experienced backline with their direct running. Then Cuthbert stole possession off Damaris Egurrola deep in enemy territory and went for goal, Endler just holding on to the ball with Kerr ready to pounce.

Eriksson and Chelsea had a huge escape on the hour. The Swede gifted possession away inside our box and sub Vicki Becho found Cascarino, whose shot got the faintest of touches from Berger to tip it onto the post. Super save.

Finishing determinedly

There followed a couple of minutes of panic in the Blues defence before we calmed things down and nearly doubled our lead, Reiten thumping the ball high into the side-netting following great hold-up play from Kerr.

Niamh Charles replaced Cuthbert, who had been harshly booked, for the final 20 minutes.

Kerr blasted wide having been put through by James, and although the offside flag was raised VAR would have overturned that decision had the Australian found the net, as many inside the OL Stadium thought she would.

Fewer than 10 minutes remained when Lyon sub Danielle van de Donk saw her shot deflected just wide off the toe of Perisset. But largely we were doing a good job at keeping the holders at arm’s length, and that theme continued until the final whistle as we dealt with one last corner to confirm our advantage heading into the second leg.

What’s next?

There is little pause for breath before our next big game, away to Manchester City in the WSL on Sunday.

Then it’s back to the Bridge for the second leg of this tie. We play Lyon on Thursday 30 March with tickets, starting at just £9 for adults and £1 for juniors and seniors, available now.

Chelsea (4-2-3-1): Berger; Perisset (Mjelde 86), Buchanan, Bright (c) (Eriksson 44), Carter; Leupolz, Ingle; James (Rytting Kaneryd 85), Cuthbert (Charles 71), Reiten; Kerr.
Unused subs Musovic, Orman, Abdullina, Fleming, Cankovic
Scorer Reiten 28
Booked Ingle 54, Cuthbert 57

Lyon (4-diamond-2): Endler; Carpenter, Gilles, Renard (c), Morroni (Bacha 55); Egurrola; Horan, Dabritz (Majri 69); Marozsan (Van de Donk 55); Cascarino (Malard 69), Le Sommer (Becho h/t).
Unused subs Belhadj, Hegerberg, Sombath, Cayman, Bruun, Benyahia

Referee Tess Olofsson from Sweden