Pep Guardiola's first league match in charge of Barcelona did not go as planned with the title hopefuls falling to an embarrassing 1-0 opening day defeat to promoted Numancia on Sunday.
Guardiola, a member of Barca's 1992 European Cup winning team, has the job of wrestling the title from Real Madrid but the omens do not look good after an insipid display.
Barca were poor travellers last season under Frank Rijkaard and the new manager and season failed to bring a change in fortune and Real can turn the screw when they face Deportivo La Coruna in Sunday's late match.
Barcelona handed a league debut to Dani Alves – a 29.5 million euro signing from Sevilla in the summer – with Lionel Messi starting in attack after inspiring Argentina to Olympic gold.
Guardiola set up Barca with a 4-3-3 – the same system as Rijkaard – with Thierry Henry starting on the left wing – a position the Frenchman clearly doesn't like.
Numancia took the lead with Mario rifling home on 12 minutes after Barca's defence failed to deal with a cross from the left.
Samuel Eto'o hit the crossbar four minutes later and Barca had several other openings – with Messi hitting the post in the final minute – but Numancia held on for a historic win.
After just one game the league now goes on international break until September 13/14 but Guardiola will probably be relieved as he bids to solve his team's troubles.
Atletico Madrid followed up their impressive midweek qualification for the Champions League with a crushing 4-0 victory over promoted Malaga on Sunday.
Dutch international Johnny Heitinga scored 26 minutes into his league debut and Diego Forlan grabbed a quick fire brace before the interval to leave Malaga down and out. Florent-Sinama Pongolle completed the rout with a debut goal.
For the first time in their history Atletico fielded a starting XI without any Spanish players – although Argentine Mariano Pernia has dual nationality – but the fans will not care as long as they continue winning.
Last season's runners-up Villarreal were left frustrated as they were pegged back to a 1-1 draw by Osasuna.
Marcos Senna, a revelation for Spain in their Euro 2008 success, netted on 54 minutes to put Villarreal ahead but Osasuna levelled 15 minutes later.
Elsewhere UEFA Cup representatives Sevilla and Racing Santander shared the spoils in a 1-1 draw with Racing equalising after Luis Fabiano had shot Sevilla into a 70th minute lead.
Champions Real begin their bid for a third successive league title at La Coruna later on Sunday.
Robinho has been left out of the travelling squad and decided to hold his own press conference on Sunday to reiterate his desire to join Chelsea.
“The problem is that (Real Madrid) did not manage to recruit,” Robinho said. (Bernd) Schuster (Real coach) isn't my father, he's my coach. He can't make me do anything.”
It was not the pre-match preparation that Real wanted as they bid to end their Riazor jinx having failed to win at Depor since the 1991/92 season.