Tito Vilanova's side secured all three points tonight despite going down to 10 men following Javier Mascherano's dismissal, as they edged a nine-goal thriller
Well-taken strikes from Jordi Alba, Cristian Tello and Lionel Messi made it 3-0 to Tito Vilanova's side inside 20 minutes, before Pizzi reduced the deficit with a penalty. Alex Bergantinos then beat Valdes with a half-volley from distance before Messi made it 4-2 with a low finish from 15 yards shortly before the break.
Pizzi grabbed his second with a fine free-kick shortly after half-time before Barcelona's Javier Mascherano was sent off for a second yellow card after an altercation with Riki. Messi completed his hat-trick with an explosive run and finish in the 77th minute, but there was still time for more drama as Alba sent a volley past his own goalkeeper Victor Valdes to make it 5-4.
The Catalan side were able to hold on, however, to maintain their position at the top of the Primera Division table.
The visitors gave a firm signal of their intent by taking the lead after just three minutes through Jordi Alba. The Spain international took a pass from Cesc Fabregas in his stride brilliantly before stroking a shot past Dani Aranzubia.
Within five minutes they had increased their lead, after a driving run and clipped pass from Messi found Tello on the right. The youngster immediately set off for goal, turning the Deportivo left-back Ayoze inside-out on the edge of the box before hammering a low shot between the legs of Aranzubia.
Not to be outdone by the goalscoring exploits of his team-mates, Messi soon added his name to the scoresheet, smashing in Barcelona's third with his left foot from 18 yards after a delightful backheel from Fabregas had pulled Deportivo's two centre-backs Carlos Marchena and Ze Castro out of position, and cleared the way to goal for his Argentine team-mate.
Despite their imperious attacking play Barcelona offered Deportivo a chance to get back in to the match when Javier Mascherano caught Pizzi with a sliding challenge as he burst into the penalty area. The referee awarded a penalty despite the visiting players suggesting the foul was outside the box, and Pizzi wasted no time in stepping up to take the spot-kick he had won, confidently dispatching past Victor Valdes.
Deportivo struck again shortly after through Bergantinos, the midfielder making it 3-2 in the 37th minute with a well-struck half-volley from the edge of the box that ricocheted off Valdes and into the back of the net. Suddenly, the hosts were back in the game, after being seemingly dead and buried so early in the contest.
The flurry of first-half goals did not stop there, though, as Messi scored the sixth goal of the half, and his second of the evening, running on to a fine outside-of-the-boot pass from Fabregas before firing a low shot into the bottom left-hand corner of Aranzubia's goal.
Any who thought the second half would not live up to the first were given a jolt in the 47th minute as Pizzi curled an inch-perfect free-kick into the top right corner from 25 yards to cut Barcelona's lead to just one.
Minutes after Pizzi had made it 4-3 Barcelona were reduced to 10 men following the sending off of Javier Mascherano for a second bookable offence. The referee Jose Paradas deemed the Argentine to have caught Riki with a flailing arm after the striker dribbled towards him, but replays showed that he got the ball and made little contact with the Deportivo player.
Messi then came within millimetres of completing his hat-trick from a set piece as his vicious free-kick from 30 yards came cannoning back off Aranzubia's left-hand post and away to safety.
Messi did eventually notch his third of the night in the 77th minute. After dispossessing Ze Castro 45 yards from goal, the Argentine powered towards the Deportivo goal before unleashing an unstoppable shot into the bottom right corner with his left foot.
A moment of madness from Alba supplied Deportivo with a lifeline, as he volleyed the ball into his own net under pressure from Riki inside the Barcelona penalty area to make the score 5-4.
Deportivo committed men forward late on as they went in search of an equaliser but Barcelona's makeshift defence managed to withstand the pressure and hold out for all three points in what was one of the most engrossing, unlikely, incredible encounters of the season.