Barcelona got their bid for a third consecutive La Liga title back on course when Lionel Messi and Gerard Pique struck to lift the champions to a 2-1 win in Atletico Madrid on Sunday.
Ten-man Valencia earlier made it three wins out of three and went clear at the top of the standings when Juan Mata and Pablo Hernandez scored in a 2-1 win at Hercules.
Barcelona spoiled Atletico's perfect start to the season with a much more accomplished performance at a typically boisterous Calderon stadium.
Messi, taken off on a stretcher in added time after a wild tackle from Tomas Ujfalusi damaged ligaments in his right ankle, poked Barca ahead in the 13th minute, seconds after a David Villa strike had ricocheted back off a post.
Atletico midfielder Raul Garcia lifted the crowd with a towering header past Victor Valdes in the 25th before Spain defender Pique outmuscled the home defence to put Barca back in front just after the half hour.
Atletico goalkeeper David De Gea kept the home side in the match with smart saves off Xavi and Pedro at the start of the second period and Villa and Messi both missed chances to make the game safe.
The Atletico fans gave Barca midfielder Andres Iniesta, scorer of the winning goal for Spain in July's World Cup final, a rousing ovation when he was replaced by Javier Mascherano.
However, Barca's win, their first under Guardiola at the Calderon, was soured shortly after when Messi was carried off and he looked in pain, clutching his face with both hands as he was stretchered around the touchline. Czech defender Ujfalusi, who had already picked up a booking, was shown a straight red card.
Barca said in a statement that Messi had sprained the external ligament in his right ankle but there was no bone damage and further tests would be conducted on Monday.
Coach Pep Guardiola called the team's performance “spectacular” against an “aggressive and intense” Atletico. “We are very pleased with the win but sad about the injury to Leo (Messi),” he added.
Unai Emery's Valencia, who kicked off their Champions League campaign with a resounding 4-0 win at Turkey's Bursaspor, took the lead in the second minute against Hercules when Spain international Mata volleyed in from a Hernandez centre.
Winger Hernandez doubled the visitors' lead in the 23rd before former Juventus striker David Trezeguet netted from the penalty spot for Hercules two minutes before the break.
Defender David Navarro was dismissed after picking up a second yellow five minutes into the second period but Hercules were unable to find an equaliser.
Valencia have nine points from three matches, two ahead of Real Madrid, who claimed a hardfought 2-1 victory at promoted Real Sociedad on Saturday, and Sevilla, who won 2-1 at Andalusian rivals Malaga in Sunday's late kickoff. Atletico and Barca have six points, level with Villarreal and Espanyol.
Messi out for at least two matches
Messi will miss Barcelona's next two La Liga matches and may be out for longer. Tests confirmed ligament damage to his right ankle and he will be unavailable for the home game against Sporting Gijon on Wednesday and Saturday's trip to Athletic Bilbao. His participation in Barca's Champions League match at Rubin Kazan on September 29 will depend on his recovery, Barca said.