The 34-year-old tore an Achilles tendon in AC Milan’s 1-0 win over Chiev on Sunday.
Beckham will fly to Finland on Monday for specialist surgery.
“A rupture of the Achilles tendon is suspected,” said an AC Milan statement.
AC Milan vice-president Adriano Galliani expects the former Manchester United star to be out for ‘probably five or six months’.
“I saw him and he was suffering. In the dressing room, I took him in my arms and told him that if he wanted, he will be with us next year,” said Galliani.
AC Milan coach Leonardo said: “Beckham’s injury makes us feel terrible. He understood immediately that he had torn his Achilles tendon.
“He is an extraordinary guy and today’s game proves it yet again. I cannot enjoy this evening considering this serious injury.”
