Barcelona wrapped up their 26th La Liga title with a sluggish victory over Levante thanks to a goal from second-half substitute Lionel Messi.Ahead of Wednesday's Champions League semi-final first leg with Liverpool, Messi began the game on the bench.The Argentina forward came on at the interval following a goalless first half and scored just after the hour.He latched on to Arturo Vidal's header and beat two defenders before stroking the ball past Aitor Fernandez.Barcelona did not have everything their own way and Levante almost spoiled the party when they twice went close to equalising in the second half.Jose Luis Morales broke clear on the left edge on the edge of the box only to fire into the stands.Then at the death Enis Bardhi's shot hit the woodwork and it bounced into the hands of Barca goalkeeper Marc-Andre ter Stegen on the line.