MADRID, April 29 (Reuters) - Barcelona gave themselves a chance of wrapping up their second successive league title this weekend when a powerful Ronaldinho strike secured them a 1-0 win at home to relegation-threatened Cadiz on Saturday.
If second-placed Valencia fail to beat struggling Alaves on Sunday, the Catalans will have an unassailable lead at the top of the table and pocket their 18th league championship.
Barcelona looked a little jaded after securing a place in the Champions League final earlier this week but Ronaldinho earned the victory that put them 11 points clear when he slammed home from 12 metres after nine minutes.
Celta Vigo stayed in the hunt for a Champions League place with a 2-0 win at Deportivo Coruna in the Galician derby as they celebrated their first league victory at the Riazor in 11 years.
The triumph came courtesy of a controversial goal by leading scorer Fernando Baiano and a late strike from his replacement Jesus Perera shortly after Depor were down to 10 men following the dismissal of centre-back Fabricio Coloccini.
The win left Celta fifth on 60 points, two behind Osasuna, but with the Navarrans hosting third-placed Real Madrid on Sunday they are now in a strong position to challenge for a Champions League spot.
Relegation-threatened Real Betis and Athletic Bilbao shared the points in a 1-1 draw in Seville, a result that was enough to keep both sides clear of the danger zone.
Ronaldinho, starting his first league match in almost a month, made an immediate impact at the Nou Camp when he put Barca in front in the ninth minute.
The Brazilian took his tally for the season to 16 goals when he met Belletti's cross with a perfectly struck half-volley after the fullback had blazed his way down the right.
Cadiz appeared unfazed by the setback and midfielder Jonathan Sesma had the ball in the net two minutes later, only to see his goal disallowed for a borderline offside.
Sesma had another chance to equalise soon after but this time lifted his shot over the bar with just the keeper to beat after a great through-ball by Matias Pavoni and 15 minutes later he was denied by a fine save from Barca keeper Victor Valdes.
The home side had a chance to extend their lead when they were awarded a penalty after Mark van Bommel was brought down as he burst into the area in the 63rd minute but Samuel Eto'o's spot kick was well saved by Cadiz keeper Oscar Limia.
Valdes also had to make a good stop to preserve the lead when he scrambled a late header by substitute Oli off the line.
But the biggest cheer came 10 minutes from time when Barca's Spain midfielder Xavi returned to action after a five-month lay-off following a serious knee injury. He is now available for the Champions League final with Arsenal and the World Cup.