Barcelona forward Lionel Messi believes the Catalan club's great rivals Real Madrid have improved since Barca beat them to win the Spanish Super Cup in August.
"Madrid have strengthened their squad well with the aim of being better this season and they have achieved that," the Argentine World Player of the Year was quoted as saying in Marca sports daily on Friday.
"They have grown since August and they are stronger than last year," he told the Madrid-based newspaper. "But we are too with the additions we have made."
Jose Mourinho's Real side, who have won nine in a row in La Liga and the Champions League, can stretch their lead over Barca at the top to four points with a win at home to Osasuna on Sunday.
Barca, bidding for a fourth straight domestic title, play later on Sunday at Athletic Bilbao.
The pick of the weekend's matches pits third against fourth, with surprise packages Levante hosting their more illustrious city rivals Valencia on Saturday.
Levante, who briefly topped the table for the first time in their 102-year history, are a point behind Barca in third and two ahead of Valencia.
Barca's game at Bilbao will reunite their Chile forward Alexis Sanchez with his former national team coach Marcelo Bielsa, the Argentine who took over at the Basque club for the start of this season.
Sanchez, who joined from Udinese in the close season, came on as a substitute in Tuesday's Champions League game at Viktoria Plzen after an injury absence of nearly two months.
Valencia will be without their Argentine playmaker Ever Banega for the trip across town after he twisted ligaments in his right knee in Tuesday's 3-1 Champions League win at home to Bayer Leverkusen.
Banega will be sidelined for four to six weeks and the injury is a further blow to coach Unai Emery after creative midfielder Sergio Canales was last week ruled out for three to six months because of a serious knee injury.
Real Betis coach Pepe Mel is under pressure ahead of Saturday's game at home to big-spending Andalusian rivals Malaga.
Promoted Betis won their opening four matches but have lost their last six and slipped to 12th.
"We are tense and anxious to get back on the pitch, angry that things have not worked out for us despite all the work," Mel told a news conference on Friday.
"We want to win to put everyone's minds at rest, as well as our own," he added.
Atletico Madrid have been their usual erratic selves this term, going seven games without a win in all competitions after a strong start, but showed what they are capable of in Thursday's 4-0 Europa League win at home to Udinese.
Spain Under-21 striker Adrian, who scored twice at the Calderon, said the win had been good for morale.
"These two straight wins were important for the team," he told reporters. Atletico beat Real Zaragoza 3-1 at home last weekend and are 10th on 13 points.
