Barcelona are still six points ahead of Real Madrid in the race for the Spanish title and Osasuna lie in second-place, due to the leaders' superior goal difference.
The Catalan side went a goal down against Seville in the 63rd minute but Samuel Eto'o equalised two minutes later. Ronaldinho then scored the winning goal with 12 minutes of the game remaining with a spectacular solo effort.
Osasuna extended their perfect home record to eight wins when they beat struggling Real Mallorca 1-0 at El Sadar thanks to an early strike from Pierre Webo yesterday afternoon.
Real Madrid moved up to third after a 2-0 win at Malaga gave new coach Juan Ramon Lopez Caro a winning start in the league.
Defender Sergio Ramos headed in the first goal from a corner and Brazilian forward Robinho added a second four minutes later with a fierce strike from 15 metres.
Villarreal, Deportivo Coruna, Valencia and Celta Vigo are all tucked in close behind, a further two points back from Real. Villarreal won 3-1 at Real Sociedad on Saturday while Valencia were held 1-1 by struggling visitors Athletic Bilbao.
