Schalke striker Klaas-Jan Huntelaar will undergo surgery after re-injuring his knee in training on Monday.

The Holland international announced on his Twitter account that he made the tough decision to go under the knife.

It's been difficult, but I've decided to undergo surgery. Recovery time will be 3 to 4 months. It's though, but a necessary step.

-- Klaas Jan Huntelaar (@KJ_Huntelaar) October 18, 2013 Huntelaar's injury threatens his chances of pushing for a place in Holland's World Cup squad next summer and certainly rules him out of Schalke's Champions League group campaign in which they have been pooled with Chelsea.

Huntelaar was only just returning from eight weeks on the sidelines with ruptured ligaments in his right knee.

A collision to the same knee in training on Monday was described as "unlucky" by coach Jens Keller.

Huntelaar, who has made just three appearances so far this season, had to be helped from the training ground by his team-mates.

"It's incredible. How unlucky can one be?" Keller told the Bild newspaper. "I have no idea what we're doing wrong."

Huntelaar said it was "just an unfortunate collision".