Carter limped out of Perpignan's 40-14 home win over Bourgoin in the Top 14 after a recurrence of an old Achilles injury. He is now set to undergo further tests on the problem.
"The pain was getting worse after about half an hour of the match and as a precaution I came off at half-time," Carter told AFP.
"It was frustrating because I really wanted to play and the team had a really good match. I'll get tests on Monday and will decide with the staff if it would be better to take several days off from training."
The game against the Ospreys will be vital to both side's hopes of qualifying for the quarter-finals. The Ospreys, who beat Perpignan 15-9 at the Liberty Stadium in Round 2 before Carter had joined the club, are level at the top of the Pool 3 table on 15 points with Leicester Tigers, with the French side trailing in third with nine.
To stand any chance of qualifying for the last eight Perpignan must gain a bonus point victory from their final two games and hope other results go their way. The Ospreys, who qualified for the quarter-finals for the first time last season, know they must take something from the game at Stade Aime Giral to set up a sixth round win-at-all-costs game with the Tigers in Swansea.
Perpignan's victory kept them in third place behind leaders Toulouse and Stade Francais in the Top 14. Meanwhile, Hook's Ospreys lost top spot in the Magners League with a 25-21 home defeat at the hands of Munster on Friday night.
Hook is hoping to use the final two rounds of Heineken Cup games against Perpignan and Leicester Tigers to prove to Wales coach Warren Gatland he is worthy of launching his side's defence of the Six Nations title in the No 10 jersey at Murrayfield against Scotland on Sunday, 8 February.