The hosts were down 1-0 after Javier Pastore’s goal and looked like a good bet to crash out of the tournament until Messi came on in the 60th minute to set up Pedro and ensure Barca went through on the away goals rule.
PSG looked sharp early with Lavezzi in particular giving the Catalans all sorts of fits in front of goal.
The visitors were in a confident mood with Messi on the bench, and Lucas Moura came close to opening the scoring with a shot that Barca goalkeeper Victor Valdes palmed away.
The French outfit continued its positive start to the encounter as Valdes was forced to tip Lucas Moura’s header over the bar after some good work by Zlatan Ibrahimovic.
However, PSG could not penetrate Barca’s back line and had to be content with a 0-0 scoreline heading into the half-time break.
Paris Saint-Germain then silenced the Camp Nou faithful in the 50th minute when Pastore and Ibrahimovic played a wonderful one-two and the Argentine slipped the ball past a diving Valdes.
PSG was up 1-0 on the night and 3-2 on aggregate, and it was just a matter of time before Messi laced his boots and made an appearance.
And that’s exactly what happened 10 minutes later, and suddenly Barca went from a team on the brink to absolutely dominant.
Andres Iniesta and Xavi tested Sirigu in quick succession, and the PSG defence was on the back foot for the first time in the game.
Barca was piling on the pressure and the breakthrough came when Messi found Gerard Pique, who layed it off to Pedro, who smashed a shot into the back of the net.
The score was tied at 1-1 on the evening and 3-3 on aggregate, but Barca was leading on away goals.
The Catalans held out for the final 15 minutes without too much bother and will appear in the last four of Europe’s most prestigious club competition for the sixth straight time.
Lionel Messi proved once again just how valuable he is to Barcelona, who will once again be one of the favorites to lift the prestigious trophy.