Midfielder won't play again before loan expires in January
Midfielder Ryan Watson has returned to Leicester City after picking up a cruciate ligament injury.
Watson, who joined the Cobblers on loan at the end of the summer transfer window, was due to stay at Sixfields until January but he has now returned to his parent club for treatment.
"It is a real blow for us and for Ryan," said boss Chris Wilder.
"I can't speak highly enough of Ryan. He has done really well for us and his attitude and desire are first class. You could tell from the games he played the sort of boy he is. I would like to thank Ryan for his efforts and thank Nigel Pearson and Terry Robinson and Leicester City for allowing us to borrow him.
"We wish Ryan a speedy recovery and hopefully we can look to resurrect the deal when he is fit again.
"We are in a terrible run of injuries at the moment but it speaks volumes for the work ethic and togetherness in the squad that the lads are getting on with things and that we have got ourselves to fifth in the table.
"This is another blow we will take in our stride and move forwards from."
Watson made five appearances for Northampton Town, and technically remains on loan with the club until January.