Senegalese international Sadio Mane said "it was just fantastic" to be back in training with Bayern Munich on Sunday three months after suffering the injury that ultimately ruled him out of the World Cup.

The 30-year-old forward has handed the German champions a much-needed boost a week ahead of their top of the table clash with Union Berlin.

Union Berlin could be two points ahead of Bayern when they meet if they beat rock-bottom Schalke later on Sunday.

Bayern lost 3-2 to Borussia Moenchengladbach on Saturday.

Mane -- who suffered a right leg injury in November and had to undergo an operation -- was all smiles when he turned up for training on Sunday.

"To have this feeling again is just fantastic," he said.

Bayern manager Julian Nagelsmann said Friday that with a full week of training Mane could be integrated into the matchday squad.

Bayern could also welcome back another key member of the squad to team training in midweek.

Moroccan international Noussair Mazraoui -- who has been out for several weeks after a medical check revealed he was suffering from a heart issue -- is expected to return on Wednesday.