In what was Pep Guardiola’s last home match in charge at the Nou Camp, Messi made sure there was a happy ending to what was an emotional night for the home fans.
The Argentine opened the scoring with a free-kick and completed his hat-trick with a trademark burst and finish. Goals two and four were from the penalty spot even though Espanyol could feel aggrieved by both spot-kick awards.
Thousands had turned out with flags and banners paying tribute to Guardiola and what he has achieved for the club during his four-year spell in charge.
Barcelona may have conceded their 2011 league title to arch-rivals Real Madrid last week, but three-time FIFA Ballon d’Or winner Messi gave the Nou Camp a boost by pulling ahead of Cristiano Ronaldo in the race for the league’s top scorer title.
Messi is now the undisputed all-time top-scorer in the history of European football, having overtaken the previous record of 67 goals scored by German legend Gerd Mueller for Bayern Munich in a single season in the 1970s.
Real Madrid win 2-1
Ronaldo scored a goal in newly crowned champions Real Madrid’s last-gasp 2-1 win over Granada, leaving the Portuguese international striker on 45 league goals, five behind Messi with one league match remaining.