Northampton boss Jim Mallinder is hoping Ben Foden hasn't broken his leg after being carried off in the 18-14 win against Bath.
The England wing left the field in the second-half following a run-of-the-mill tackle from Bath's Tom Biggs, and departed from the ground wearing a surgical boot.
"It's an ankle injury but I don't know a lot more about it than that," said Mallinder.
"The doctor thinks that it's not broken. We're hopeful it's just a strain."
Stephen Myler kicked five penalties as Northampton made it three wins out of three in the Aviva Premiership.
Foden's replacement, Tom May, wrapped things up with a drop-goal four minutes from time.
"Any win away from home is pleasing," said Mallinder.
"In terms of performance we're still not playing as we want.
"We've got a run of two home games coming up though and after a short turn-around - Sunday to Friday - to get the win is pleasing."