party is World Player of the Year Lionel Messi, who came off the bench and scored twice on his return from injury in Wednesday's 4-0 last 16, first leg success at home to Getafe in the Cup.
Lionel Messi was given a rousing ovation by the adoring home fans when he replaced Andres Iniesta in the 64th minute at the Nou Camp, the Argentina forward's first appearance since straining a thigh muscle in November.
The injury was the latest in a string of problems that dogged him during 2013 but he said he was now "free of pain" and full of desire to help Barca in their bid for La Liga, Champions League and King's Cup glory.
"I am as excited as ever," he told Barca's TV channel after the Getafe game, adding that he would consult coach Gerardo Martino and club medical staff to decide if he can start against Atletico.
"Before I had got used to playing with pain and today... I felt very good physically," the 26-year-old said.
"Beyond the injuries I just want to play again. If I can be in the team (on Saturday) I will be there."
Real have their King's Cup last 16, first leg at home to Osasuna to negotiate later on Thursday before they travel to Barcelona to face mid-table Espanyol, while Monday's game sees European hopefuls Villarreal, in sixth, hosting fifth-placed Real Sociedad (2100).