It took Leganes just four minutes to break the deadlock as Barcelona were caught off guard. Sergio Gonzalez, who was unmarked inside the penalty box, converted a clinical header from Oscar Rodriguez's curling corner to hand his team an expected lead. Barcelona started to dominate proceedings as the game progressed, though, and had several opportunities in the first half to score the equaliser. However, star striker Robert Lewandowski had a nightmare outing in front of goal.
The Poland international squandered a major chance in the 10th minute when Raphinha created the perfect goalscoring opportunity for him, failing to steer the ball home from barely two yards out. Raphinha could have found the back of the net himself just after the half-hour mark when he attempted a first-time volley from Alejandro Balde's low cross, but Leganes goalkeeper Marko Dmitrovic did an exceptional job in parrying the ball away as it hit the crossbar and went out.
The Blaugrana continued to create chances after the break as they dominated possession, however, some resolute defending from Leganes kept the opposition at bay. Both Lewandowski and Lamine Yamal were subbed midway into the second half after failing to make an impact as Gavi and Ferran Torres were brought in to shape up the attack, however, Leganes held on for a shock 1-0 victory that will have big repercussions for the La Liga title race.