The victory earned the Spanish champions a 5-2 aggregate victory but an otherwise sloppy performance will have done little to allay fears that the Catalans have gone off the boil after winning just one of their last five league matches.

Saviola, who also scored both goals in the 2-0 win in last week's first leg, strengthened his case for a regular place in the starting line-up with another fine individual performance.

His first came when he bundled the ball in from close range on 16 minutes after Alaves keeper Nicolas Ardouin palmed the ball into his path following a Ronaldinho free-kick.

The pocket-sized Argentine made it 2-0 four minutes later when he ballooned a header over the French keeper after midfielder Thiago Motta had dinked a neat pass into the area.

But the Catalans relaxed too soon and Alaves were back on level terms in the game by halftime.

Brazilian forward Wellington Paulista chipped the ball over Albert Jorquera after a neat one-two on the edge of the area and fellow countryman Arthuro left the Barca keeper standing when he curled a superbly struck free kick around the wall from 25 metres out.

Wellington had a great chance to put Alaves ahead on the night when he broke free and rounded Jorquera early in the second half, but defender Carles Puyol managed to scramble the Brazilian's shot off the line.

Saviola ended any hopes of a comeback when he completed his hattrick soon after, volleying home from 15 metres out after Xavi had beaten the offside trap with a chipped pass over the Alaves back four.

The majority of the remaining ties will be played on Wednesday. Real Madrid host struggling Real Betis at the Bernabeu on Thursday after the two sides fought out a 0-0 draw in last week's first leg.