Valencia's failure to beat Alaves at home on Sunday would give Barcelona their second successive championship.

Even if the Valencia beat their struggling Basque visitors, then a Barcelona victory at Celta Vigo on Wednesday will clinch the title.

Ronaldinho's goal after nine minutes was enough to claim all three points.

The World Player of the Year has scored many more spectacular goals during his career but a simple shot from right on the penalty shot sufficed this time.

Ronaldinho found the target after his Brazilian compatriot Belletti had provided the crucial pass from out on the right flank.

Barca's 90,000 fans in the Nou Camp were silenced two minutes later when Jonathan Sesma scored only for the chants of 'Campeones, Campeones' to start up again when the Cadiz striker's effort was ruled out for being him just offside.

Samuel Eto'o was given the chance to add to his tally of 24 goals this season when Cadiz defender Magnolo Berizzo tripped Mark Van Bommel just after the hour but the first division's leading scorer sent his penalty straight to Cadiz keeper Oscar Limia.

Perhaps the biggest cheer of the night was not produced for Ronaldinho, Eto'o or any of the other men who have taken Barca to the verge of their 18th league triumph in recent months but midfielder Xavi Hernandez.

The Spanish international made his entrance nine minutes before the end to take part his first game for five months after being out of action with damaged right knee ligaments.

The defeat still leaves Cadiz, last season's second division champions, still in dire trouble and in danger of an immediate return to the lower division.

Celta Vigo continued their surprising season with a 2-0 win at local Galician rivals and fellow UEFA Cup contenders Deportivo La Coruna on Saturday.

A goal in each half from David Silva and Jesus Perera gave Celta three vital points to keep them in fifth place and still with a good chance of qualifying for the Champions League.

Silva put the visitors ahead from close range after 34 minutes, scrambling the ball into the net following a Nestor Canobbio corner.

Perera then completed Celta's joy with an angled left foot shot from side of the area three minutes from the whistle.

Deportivo's misery was compounded by having their World Cup-bound Argentine defender Fabricio Coloccini sent off 10 minutes from time after recieving his second yellow card.

Real Betis were held to a 1-1 draw by fellow strugglers Athletic Bilbao, a result that does neither side any favours and leaves both of them still worryingly close to the relegation zone.

Betis winger Edu sent a crafty chip into the six-yard box after 24 minutes and his Brazilian compatriot Robert was on hand to head home the opener but the Basque visitors equalised through a Jesus Lacruz goal after 65 minutes.