The Real Madrid striker pulled up in training because of pain in his left thigh.
Victory for Barcelona took them to within a point of third-placed Deportivo Coruna and kept second-placed Valencia in their sights.
Ruben Baraja scored two goals as Valencia rallied to sink regional neighbours Villarreal 4-2 in the Spanish League.
Athletic Bilbao climbed up to fifth place in the Spanish Primera Liga with an uninspiring 1-0 win at home over bottom club Espanol.
Real, bidding for a 10th European Cup, have the easiest task on paper away to a Partizan Belgrade side.\n\n
AS Roma and Juventus lost on their domestic returns from midweek UEFA Champions League action as their miserable starts to the season continued. In England, frontrunners Liverpool and Chelsea fared better with wins while Valencia top the table on goal difference in Spain and Lazio, Udinese and champions Inter Milan share the lead in Italy.
A 5-0 victory over Racing Santander left Real three points behind Barcelona with three games to play after this weekend's matches.
The ace striker scored both the goals in 2-0 win over Real Sociedad that revived their hopes winning the Spanish league.
The Real Madrid captain played over 500 matches and helped the team to three European Cups and six league titles.
World champion Viswanathan Anand dropped out of contention for a top finish in the Bilbao Grand Slam final chess tournament after losing from a better position to Levon Aronian of Armenia in the eighth round.
Vicente del Bosque is still unsure about his future as Real Madrid coach, despite landing his fourth major trophy in less than four years in charge.
Real must beat Athletic Bilbao in their concluding league match to emerge Spanish champs. \n\n
A roundup of weekend action in the main European leagues.\n