Kerr had one shot saved and created a couple of openings but was otherwise well-marshalled by the Barca defence. Adding to her frustration was a harsh booking.
Chelsea must now win in the Nou Camp on Thursday to reach the final in the Dutch city of Eindhoven on 3 June.
The other semi-final first leg,between Wolfsburg and Arsenal,is on Sunday.
Saturday’s match was packed with players who will be heading Down Under for the Women’s World Cup,though one who did not make it was Kadeisha Buchanan,a key defender for Australia’s group opponents Canada. She has a leg injury and was present but wearing a protective boot.
Barcelona fielded five of the XI who destroyed Chelsea 4-0 in the 2021 final while six of the Chelsea side had started that ignominious night in Gothenburg,including Kerr.
Among the absentees was injured England centre-half Millie Bright. With Buchanan also out,it was a makeshift back five that faced a Barcelona team which had won 35 of 36 matches this campaign and scored 35 goals in their previous eight European ties.
Goal No. 36 wasn’t long in coming. Norway’s Graham Hansen picked up the ball on the right,drifted inside past several ineffectual challenges,and whipped a 20-yard shot inside the far post.
Chelsea,with co-owner Todd Boehly among the 27,697 in attendance,were then penned inside their own half,the occasional long ball for Kerr to chase their only outlet.
It was midway through the half before the home fans had something to get excited about with Kerr and Guro Reiten combining to threaten on a trio of occasions.
A one-two with the Norwegian led to a Kerr shot that had Sandra Panos scrambling across goal to save.
The Matildas captain then set up Reiten to score,only for Kerr to be ruled marginally offside.
The Aussie then again released Reiten who rounded Panos only for Bronze to clear off the line.
That,though,was largely it for Chelsea’s attack with Kerr increasingly isolated even after Lauren James,sister of England and Chelsea men’s defender Reece,came on to support her.
“We were aware of the direct game,and Kerr passing to Reiten,so we stopped that,” said Barca coach Jonatan Giraldez.
Making Kerr’s afternoon worse was a harsh booking for a late challenge on Lucy Bronze,though she remains eligible for the second leg.
Marta Torrejon’s header stuck the post for Barcelona and Ann-Katrin Berger denied Sweden’s Fridolina Rolfo,but Chelsea kept the score down and the tie alive,just.
“I’m grateful to be in a position where the tie isn’t over after 25 minutes,” said Chelsea boss Emma Hayes.
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