Isaac Success is a major doubt for Watford’s trip to Swansea City on Saturday after missing training this week with a muscle injury.

The Nigerian attacker made his first start for the Hornets in Sunday’s 1-0 win at Middlesbrough but could miss out on the game at the Liberty Stadium.

Head coach Walter Mazzarri said: “He didn’t train for the whole week with the team so he is a doubt for the game. He might not be available.”

The Italian added: “After I substituted him [on Sunday] because the physio told me during the game he was already hurting. I tried to keep him on as much as I could during the game.

“After the 90 minutes when we were back in the dressing room they had a look at him and confirmed he could not train for the next couple of days because of a muscular problem. Now we will see.

“Even in the past if you remember I’ve been saying he hasn’t trained regularly because of his muscle problems. He has been having problems in the upper side of the right leg. But I’m not a physio so I can’t confirm 100 per cent for you.”

If Success is ruled out it will ensure an immediate recall for Odion Ighalo. Mazzarri insists the striker handled being dropped last weekend as a true professional and is keen to prove his worth in the first team.

The Hornets boss said: “To all the players I tend to speak to them always face to face. I did it with Odion for the whole week prior to the game and as a great professional that he is he understood it very well.

“Of course I know that now he is looking forward to getting back into the starting XI and showing he belongs there. He was also ready to enter as a sub against Middlesbrough but we didn’t need it. But he was ready to play.”

Miguel Britos is fit for this weekend’s trip but Craig Cathcart remains sidelined with a groin injury.

Daryl Janmaat started training today but the Swansea game will come too soon for him while striker Stefano Okaka is close to returning to training.