NORTH Melbourne defender Daniel Nielson has been stretchered off in the opening quarter against St Kilda after being concussed at Etihad Stadium.

The 21-year-old came off second best in a marking contest when St Kilda forward Josh Bruce's knee accidentally made contact with his head.

Play came to a halt for five minutes, as medical staff assessed Nielson and immediately placed a neck brace on him as a precaution.

He was eventually carted off the ground by the motorised stretcher and taken down into the rooms.

Nielson was playing just his seventh AFL game after debuting earlier this year in round 16 against Fremantle.