Hayes says the game was over even before it started as she admitted that Barcelona were so superior against Chelsea.
Chelsea were rocked after just 33 seconds when Fran Kirby's attempted clearance looped into her own net off the unlucky Melanie Leupolz.
Barcelona got their second on 14 minutes through Alexia Putellas, before midfielder Aitana Bonmati added to the West Londoners’ misery inside 20 minutes.
Chelsea were able to contain the Catalans for more than 15 minutes but failed to get a sight of goal, and were further punished by a trenchant counterattack which was led by Lieke Martens, who gave a cutback pass for Caroline Hansen to tap home for Barcelona’s fourth goal nine minutes before halftime and that was enough to beat Hayes’ side.
Speaking to the media after the game Hayes said: “It's been a wonderful season for us, but against Barca was difficult because the game was over before it began and that's what is so difficult to reflect on.
"To concede so early, we had two good chances and then they got the second through the penalty.
"Ann hasn't had a save to make and we've lost 4-0, but the damage was done, I'm proud of the second half performance, the players gave it everything.
"Congratulations to Barcelona, they're worthy winners, deserving of the title and it's something we will learn from because this is the next step, we showed some naivety at times."
