Barcelona and Atletico Madrid will put their Liga title chase to one side when they meet in the Champions League on Tuesday.
The sides currently occupy the top two spots in the Spanish top flight - Atleti are one point clear of second-placed Barca - and clash this week in the first leg of their quarter-final tie at Camp Nou.
There has been no previous meeting between the clubs in continental football, but their three domestic fixtures this season point to this being a hotly-contested encounter.
Barca edged the Supercopa de Espana on away goals after both legs ended all square in August, while the Liga meeting in January finished goalless.
Despite their proximity in La Liga, Barca head into the last-eight tie with far greater experience of Europe's premier club competition.
The Blaugrana will be looking to extend their record of having contested the semi-finals in the last six seasons, while Atleti are in the quarter-finals for the first time since 1997 and have not reached the last four for 40 years.
Current Atleti coach Diego Simeone was in the side that lost 4-3 on aggregate to Ajax in the quarter-finals 17 years ago.
The men from the Spanish capital have not won at Camp Nou since a 3-1 league victory in 2006, when Fernando Torres - now of fellow quarter-finalists Chelsea - netted a double.
That said, Barcelona do not have the best of records against Spanish opponents over two legs in continental competition, losing five of their nine ties, but have lost just one of their last 26 European home match-ups.
Atleti have taken many by surprise with their sensational form this season, with Simeone keen to maintain the feel-good factor at the club.
"We are enjoying the situation day by day, minute by minute, training session by training session and game by game," he said after Saturday's 2-1 win at Athletic Bilbao.
"That is how we feel strong and we will continue like that because we don't want to get away from that line of thinking."
The hosts will be without goalkeeper Victor Valdes, who is likely to have played his last match for Barcelona after being ruled out for the season with a knee injury.
Javier Manquillo (neck) remains sidelined for Atleti, while Raul Garcia is ruled out through suspension.
Barcelona knocked out Manchester City to reach this stage, while Atleti disposed of AC Milan.
On an individual level, Lionel Messi is four goals short of Raul's Champions League goalscoring record of 71 and is bang in form, finding the net nine times in his last five appearances in all competitions.