Barcelona moved level once more with Real Madrid at the La Liga summit with victory at Real Zaragoza.

Lionel Messi continued his remarkable goalscoring form with a hat-trick for the Catalan side.

The Argentina winger, who also scored a hat-trick in his last league match against Valencia, opened the scoring with a header after five minutes and added two more after the break to send his side 3-0 ahead.

That should have made the game safe for Barca, but Zaragoza rallied with a brace from substitute Adrian Colunga to set up a nervy ending.

Messi, however, quickly stamped out the threat as he embarked on another mazy run to earn a 90th-minute penalty which Zlatan Ibrahimovic, who until then had been profligate, slammed home for his first league goal since February 14.

Coach Pep Guardiola had earmarked Barca's three league games in the upcoming week as crucial to their hopes of retaining their title and after Madrid won 3-1 against Sporting Gijon yesterday, it was his star man who made sure they kept pace at the top.

Messi took just five minutes to open the scoring with a well-placed header from six yards.

Pedro found space down the left flank and floated a cross to the unmarked winger who directed his header back across goal to wrong-foot goalkeeper Roberto.

It was the worst possible start for Zaragoza, who sit three points above the drop zone, and they had to ride their luck early as Gerard Pique's deft backheel flew straight at Roberto while Yaya Toure shot wide.

A rare Zaragoza break was snuffed out when Dani Alves showed his pace to deny Humberto Suazo, who had been set loose on goal, with a diving tackle.

Ibrahimovic should have put Barca further ahead on the hour mark when unmarked he diverted his header from a corner across the face of goal.

The hosts' threat dimmed after that miss before Messi lit up the contest with a fabulous solo goal after 66 minutes.

He bundled a defender off the ball to gain possession on half way before setting off on a intricate run that took him past two would-be tacklers before sliding his shot across an exposed Roberto.

It was a stunning goal and the gulf in confidence between Messi and his team-mate Ibrahimovic was highlighted after 76 minutes when the Swede somehow shot wide of an unguarded net after Pedro had played him in.

Messi showed him how to finish two minutes later as he completed his hat-trick.

He did so in signature style when he picked up the ball just outside the area and cut inside before placing a left-foot shot in at the near post.

Remarkably, the strike meant Messi had scored Barca's eight previous goals in the league and marked his 33rd in all competitions.

Barca should have been home and dry at that point, but Zaragoza pulled two goals back in the space of four minutes through substitute Colunga.

The 25-year-old striker was sent through on goal down the left flank in the 85th minute and slid a neat finish across Victor Valdes.

The Barca defence was caught flat-footed again moments later, this time with a more central ball, and Colunga again showed composure to roll the ball in and threaten an astonishing turnaround.

But from the kick-off Barca went forward and Messi ran rings around the defence in the area, twice beating Matteo Contini before the dazzled defender hacked him down as he was about to shoot.

Ibrahimovic stepped up to take the spot kick and hammered it into the corner to end his goalscoring drought.