Cardiff City's Anthony Pilkington will unavailable for at least three weeks through injury.
Bluebirds' manager Russell Slade said the club think the winger has "probably" suffered a "grade two" tear to his hamstring in the 1-0 win against Watford.
Meanwhile Cardiff are playing down concern over goalkeeper David Marshall,
Cardiff are monitoring a groin problem but say there are ''no immediate fears'' over Marshall.
Saturday's victory at Vicarage Road was the Welsh club's first league win away this season, but was marred by Pilkington's injury.
"It could be three to four weeks [out] which is a blow," said Slade.
"There are also players on the bench that are chomping at the bit to stake a claim, so somebody else has got to take their chance, that's what it's about."
|Cardiff City manager Russell Slade|
|"Today we finally nailed it. We're delighted because it was against a good team as well and a team who are competing near the top."|
Adam Le Fondre scored the only goal of the game as City earned their first league win on the road against the Hornets.
The striker tapped home the winner from close range after Kenwyne Jones's header came back off the post.
"The changing room's absolutely thrilled," said Slade.
"We've got the monkey off our back and the group was very strong, very resolute and we persevered.
"We kept tight and that's how you win at difficult places like Watford.
"I saw the signs at Birmingham and we got a 0-0 there and possibly could have got a result.
"Today we finally nailed it. We're delighted because it was against a good team as well and a team who are competing near the top."
Eighth-placed Cardiff are now level on points and below Watford on goal difference, just six points behind top-of-the-table Derby.
Slade hopes the triumph will help give momentum to their promotion push.
"I think we are getting better, I think we are getting stronger with what we are doing and I think the players are starting to enjoy it.
"To win in the fashion that we did today, where we needed to put our bodies on the line, is pleasing because that means, the players will gain confidence from that when we go away again.
"We are going the right way."
Cardiff, who have won their last five home league matches, are next in action against Rotherham United in the Welsh capital on Saturday 6 December.