Barcelona's Lionel Messi reacts following a goal scored by Leganes' Unai Lopez. (Reuters)
Title hopefuls Barcelona need to capitalise on a rare lapse by Real Madrid if they are to take full advantage of Valencia's midweek success against the leaders of La Liga.
The Catalan club must prevail at in-form Atletico Madrid on Sunday to step up the pressure on their rivals, whose 2-1 defeat at Valencia on Wednesday was only their second of the season.
Real, just one point clear of Barca and three ahead of Sevilla, play later on Sunday at Villarreal.
Barca, still reeling from their 4-0 defeat at Paris Saint Germain in the Champions League on Feb. 14, were booed last Sunday when they needed a late Lionel Messi penalty to beat strugglers Leganes 2-1 in their latest La Liga game.
"We're not going through our best moment of form," Barcelona defender Gerard Pique told reporters this week. "We're focused on finding solutions.
"The most important thing is to get back to playing the way we like to play."
Real's defeat at a struggling Valencia, however, has given Barca an opportunity to move top of the standings, at least for a few hours.
Real, hoping to capture the La Liga crown for the first time since the 2011-12 campaign, are starting to look vulnerable.
They conceded two goals in the opening nine minutes at Valencia -- a deficit that Zinedine Zidane's men could not overcome.
Atletico have had their struggles and are in fourth place, seven points behind Real. But they appear to be hitting their stride. The latest evidence was a 4-2 triumph at Bayer Leverkusen in the Champions League on Tuesday.
Atletico handed Barcelona a scare earlier this month in the King's Cup semi-finals when they drew 1-1 in the second leg at the Camp Nou, although Barca reached the final 3-2 on aggregate.
Now Luis Enrique's men must rediscover their defensive solidity against an Atletico attack boasting a red-hot Kevin Gameiro, who followed his hat-trick in Sunday's 4-1 win at Sporting Gijon by scoring again and setting up another at Leverkusen.
Fernando Torres, Antoine Griezmann and Yannick Carrasco have also been on target of late.
Real have won just one of their last four away games in La Liga and face a tricky trip to Villarreal, who have lost only twice at home this season.
Third-place Sevilla head into Saturday's city derby at Real Betis on the back of Wednesday's 2-1 home win over Leicester in the Champions League.
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