Women's Champions League holders Barcelona have dominated the competition in recent years but show signs of losing their edge as they face Chelsea in the semifinals for the third consecutive season.
Barcelona, who have lifted the trophy in three of the last four editions, are determined to prolong their era of success as they host Chelsea on Sunday in the first leg.
However Pere Romeu's side are not yet the unstoppable force they were under his predecessor Jonatan Giraldez, and Chelsea have taken a step forward with former Lyon coach Sonia Bompastor at the helm.
Barcelona edged the Blues 2-1 on aggregate in each of the last two seasons at this stage, but this year Chelsea have reasons to believe they can earn revenge.
Barcelona still possess plenty of stars, including two-time Ballon d'Or winners Aitana Bonmati and Alexia Putellas, but have also lost several big names.
Chelsea and England duo Lucy Bronze and Keira Walsh will face their former side, while Mariona Caldentey signed for Arsenal, who face Lyon in the other semifinal.
Caroline Graham Hansen was arguably the best player in the world last season, even as teammate Bonmati won the Ballon d'Or.
The Norwegian winger is still an explosive threat on the right flank but her form has dipped a little, which is the case for several players.
After battling back from a severe knee injury, Putellas has lacked consistency, although she is still capable of the sublime, while Fridolina Rolfo is in a similar position.
Youngsters like Vicky Lopez and Sydney Schertenleib are promising and finding their footing but have not yet established themself as key players.
The amount of success Barcelona have enjoyed in recent years may also be a factor – it is hard to have the same hunger with a belly full of trophies.
Meanwhile the opposition in Spain and in Europe is improving year on year.
Barcelona suffered a first ever defeat against rivals Real Madrid in March, their second loss of the league campaign.
They were also undone at Manchester City earlier in the Champions League.
Of course, with the quality they have, Barcelona could yet end the season with every trophy they are competing for.
"This team is used to playing knock-out games like this, top level games," said Barca coach Romeu.
"We've been doing that against Chelsea in the last few years and the games have been very even."
'THE GAP IS CLOSING'
Barca won the Spanish Super Cup, have reached the Copa de la Reina final and are top of Liga F.
Ruthless thrashings of Wolfsburg and Atletico Madrid show the Catalans are still the team to beat.
"Our objective is to win everything, you know that, and we're alive in all competitions," Barcelona midfielder Patri Guijarro told Mundo Deportivo.
"Why can't we do it again? That's what we want."
Chelsea are angling for a quadruple of their own this season but will be without Lauren James for the trip to the Johan Cruyff Arena.
The Blues beat Barca 1-0 at the Olympic Stadium last season thanks to Erin Cuthbert's strike, but a 2-0 reverse at home ended their dream of winning the competition for the first time.
"The gap is closing and it's a two-legged tie, anything can happen," Cuthbert warned.
"They've historically been the best for a number of years now... there's no better test than going up against the best."
Three-time champions Barcelona, meanwhile, still have Lyon's record of eight trophies as their long-term ambition to emulate.