Sam Allardyce has put his Sunderland players on red alert as they attempt to shackle man-of-the-moment Dimitri Payet.
The 28-year-old France international has made a blistering start to life in the Barclays Premier League since his £10.7million summer switch from Marseille, and turned in a fine individual display in the Hammers' 5-1 FA Cup demolition of Sky Bet championship Blackburn, in which he scored twice.
Former Irons boss Allardyce has cited Payet's contribution as the main catalyst for the strides the club has taken under successor Slaven Bilic, and he knows he poses a major threat to the Black Cats' hopes of extending their unbeaten run to three games at Upton Park on Saturday.
The 61-year-old said: "He's one that we have to watch - but there are many players from West Ham that we need to look at.
"There's no doubt about it, he's been the outstanding difference because while he was injured, it was probably the worst run of results Slaven has had when he wasn't playing.
"It shows what a difference one special player can make to your team."
The Hammers have not lost on their own park since suffering back-to-back defeats by Leicester and Bournemouth in August, and that represents a major challenge for a resurgent Sunderland, who have given their survival hopes a significant boost with a battling draw at Liverpool and a famous victory over Manchester United in their last two games.
Allardyce said: "What gives you belief is drawing at Liverpool after being 2-0 down, and beating Manchester United gives you more belief.
"There's an extra belief in the camp at the minute - but we have got to go out and take that belief and make it a reality. We have got to perform on Saturday at the highest level.
"We have got a task to go and meet head-on and try to get a result. The only way we will do that is by being at our best and paying attention to one very exceptional player for them at the moment.
"They have got a lot of exceptional players, but Payet at the minute is the game-changer for them, he's the game-winner for them."
The Wearsiders have been boosted by the return from injury of defenders Younes Kaboul and Billy Jones and midfielders Jan Kirchhoff and Sebastian Larsson.
However, it is a man still making his way in a red and white shirt who could be the ace in Allardyce's hand.
January signing Wahbi Khazri scored one goal and made the other in the 2-1 win over United, and his manager has challenged him to deprive Payet of the headlines this weekend.
Allardyce said: "He's an unknown commodity at the moment. People don't quite know how he plays or how good he is or what are his strengths or what are his weaknesses because he has not been here that long, so at the moment, he's taking full advantage of that.
"Certainly at West Ham, I suppose he's got to try to outshine Payet if he wants a challenge, and it would be very nice if he could do that."
Source: PA
