GABRIEL OBERTAN faces up to four months on the sidelines after suffering another serious hamstring injury.

Obertan has undergone surgery in France this week after suffering a recurrence of the same hamstring problem that left him on the sidelines in September.

Having been involved in five of the opening seven games of the season, Obertan damaged his hamstring in training prior to the 6-1 defeat at Manchester City.

That injury did not require surgery, but having started edging his way back towards fitness, the French winger has broken down again.

His latest setback will potentially rule him out until the end of March, and places a huge question mark over his future with the Magpies given that he is due to become a free agent in the summer.