Barcelona opened the scoring but Inter Milan replied fiercely to register a 3-1 victory at San Siro in the UEFA Champions League semi-finals on Tuesday. Pedro Rodriguez gave the Catalans the lead on 19 minutes after shooting home a Maxwell cut-back. But Wesley Sneijder brought the score level on the half-hour mark after coming unmarked to connect with Diego Milito's deft pass in the area. Shortly after the interval, Maicon put the hosts ahead upon beating a defender to the ball to score from close range. Diego Milito completed the rout with a point-bank effort on 61 minutes. Former Barca hitman Samuel Eto'o whipped in a cross that Sneijder headed towards the Argentinean ace, who made no mistake with the goal at his mercy. Barcelona will face Inter in the second leg at Nou Camp on April 28th.