Malaga stunned Barcelona with a 1-0 victory at Camp Nou to end the hosts' 11-game winning streak and prevent them from taking the overnight lead of the Spanish league.
Atletico Madrid, six points adrift of Barca in third, will look to rebound from last weekend's 2-0 reverse at Celta Vigo when they host Almeria.
Messi admitted on Thursday that he had a lot of problems both on and off the pitch last season and said that he is motivated to return to his top level in 2015.
Lionel Messi and Luis Enrique appear to have agreed an uneasy truce but hostilities could break out again if the Argentina forward's form dips.
Lionel Messi kept up his scoring streak by netting a hat-trick as Barcelona swept aside an outclassed Levante 5-0 in the Spanish league on Sunday.
Bartomeu testified before judge after being indicted for a possible charge of tax evasion, which saw the club not pay 2.8 million euros to the Spanish treasury.
Real kick off the weekend in the title race on Saturday afternoon after Sevilla open the weekend's affairs with a derby against struggling neighbors Cordoba.
Josep Bartomeu reiterated at a court appearance on Friday that neither he nor the club intentionally committed tax fraud in the signing of Brazil forward Neymar.
Messi scored one goal and set up another to help Barcelona beat Villarreal 3-1 in the first leg of their Copa del Rey semi-final.
Lionel Messi scored one goal and played a part in four more to lead Barcelona to victory at Athletic Bilbao on Sunday as they reduced Real Madrid's lead to one point.
Caballero said Barcelona are not the formidable force of recent seasons and the EPL side will face them without fear in their Champions League.