Adriano scored twice as Barcelona brushed aside the feeble challenge of Al-Sadd in Yokohama to set up a FIFA Club World Cup final meeting with Santos - but the win was overshadowed by a serious injury to David Villa.
The European champions were in complete control from the first whistle to the last, although they were given a helping hand by Al-Sadd goalkeeper Mohamed Saqr.
Saqr's hesitation presented the opener to Adriano, who fired a second under the body of the keeper to make it 2-0 at the break.
Seydou Keita and Maxwell added another two in the second half to complete a comprehensive win, but it was not all good news for the Catalans with Villa, who had been linked with a move away from the Nou Camp next month, taken off in the first half after suffering a fractured shinbone in his left leg.
Barcelona dominated possession early on, but their moves kept breaking down on the edge of the area as Al-Sadd defended deep and in numbers.
Villa almost capitalised on a defensive mistake when a poor clearance let him in, but his shot was weak and saved by Saqr. And the goal when it came in the 25th minute was a gift.
Pedro's cross from the left was too long and touched back to Saqr by Nadir Belhadj at the far post.
Perhaps expecting the former Portsmouth man to just clear the danger, which would have been the sensible option, Saqr hesitated and when he did finally react could only stab his clearance into the legs of the onrushing Adriano and the ball rebounded into the net.
Villa followed in to score after Andres Iniesta's fierce shot had been pushed away by Saqr, but the effort was correctly ruled out for offside.
The Spain forward then had to go off after picking up an injury in a tackle - later diagnosed as a fractured left tibia - with Alexis Sanchez coming on. The Qataris could barely get a touch and Adriano grabbed his second two minutes before the break with Saqr again at fault.
Thiago Alcantara played him in down the right of the area and Adriano cut inside and fired home a shot which crept under the keeper's dive.
Barca's concentration wandered at the end of the half and former Marseille striker Mamadou Niang almost caught them out twice, but was unable to test Victor Valdes.
Lionel Messi was finding plenty of space and danced through tackles before shooting just wide of the far post at the start of the second half.
Iniesta then had an attempt blocked after fashioning a shooting chance, while Saqr went some way to making up for his first-half mistake with a flying save to keep out Messi's free-kick.
But he was beaten again in the 64th minute when the Argentinian slipped in Keita to make it 3-0.
Maxwell added a fourth in the 81st minute when he fired home from a tight angle, with the unorthodox Saqr trying, and failing, to save the shot with his feet.