MADRID - Barcelona maintained their slim chances of retaining their La Liga title as they came from behind to beat Athletic Bilbao 2-1 at the Camp Nou on Sunday. Aritz Aduriz's opener five minutes into the second-half had Barca on course for a fourth consecutive defeat in all competitions. However, the Catalans showed fine spirit to respond as two goals in as many minutes from Pedro Rodriguez and Lionel Messi handed them all three points.Victory lifts Barca into second place, two points ahead of Real Madrid having played a game more, but still four points adrift of leaders Atletico Madrid with four games remaining. Defeat for Athletic also hots up the race for fourth place as the Basque side now lead Sevilla by just three points with the two sides set to meet next weekend.After a difficult 10 days which saw his side eliminated from the Champions League, lose the Copa del Rey final to Real Madrid and see their title chances dented by defeat at Granada last weekend, Barca boss Gerardo Martino hailed his players resolve. "In the first half I was thinking it would be one of those days because it is not normal that a team has so many chances and doesn't score."They kept playing and with a lot of heart in a difficult situation. More than just playing good football, which they always do, they showed a lot of courage and heart." And Javier Mascherano insisted they have to keep the pressure on Atletico and Real to ensure they remain in a position to take advantage of any slip ups in the final month of the season. "We need to cling on to the little chance we have, there is no point in the two teams above us slipping up if we don't win our games," he told Canal Plus. "We are missing a lot of chances. Once again we had to come from behind, but that is the attitude that we have to show. We played well albeit we found it difficult to score." Barca had the majority of the chances early on as Pedro wasted the first opening of the game as he placed his shot too close to Gorka Iraizoz before the Athletic goalkeeper also smothered an effort from Messi.It was the visitors who nearly went in front in spectacular style on the half hour, though, as Aduriz sent a stunning overhead kick crashing off the inside of the post and Jose Manuel Pinto reacted well to parry Markel Susaeta's follow-up effort. Barca were shocked into action by that scare and should have been in front moments later when Alexis Sanchez turned Pedro's low cross on to the crossbar.Iraizoz then made two more comfortable saves from Pedro and Sanchez to keep the scores level at the break and things got even better for Athletic five minutes after the restart when Aduriz's low strike this time found the bottom corner of the net. Barca then laid siege to the Athletic goal as Pedro again shot straight at Iraizoz when clean through before Messi also wasted a great chance when he pulled his shot wide of the target.The hosts did finally find a way through 18 minutes from time in somewhat fortunate circumstances as Sanchez's intended shot fell perfectly into the path of Pedro to tap home his 19th goal of the season. Two minutes later Barca had turned the game on its head as Messi was felled on the edge of the area by Oscar de Marcos and picked himself up to thump the resulting free kick low into the far corner.Barca should have extended their lead as Javier Mascherano and Cristian Tello wasted great opportunities on the counter-attack. And they were nearly made to pay when Mascherano had to make a last-ditch challenge to prevent Mikel Rico equalising in stoppage time.