Tottenham manager Mauricio Pochettino fears Harry Kane's performances have been affected by the protective mask the striker has worn in recent weeks.
The striker broke his nose during the north Londoners' FA Cup defeat to Crystal Palace after being caught with an elbow and underwent an operation to repair the damage.
Kane missed the Europa League clash with Fiorentina due to the injury and has failed to score in both of the games he has sported the protective headgear in.
The 22-year-old was guilty of a glaring miss against West Ham and Pochettino is concerned that the mask has restricted Kane's peripheral vision.
“He’s playing with a mask and sometimes it can disturb you,” the Argentine told the Guardian.
“Maybe it’s easier for Nemanja Matic [the Chelsea midfielder, who has also worn a mask] or different players that play behind, because creativity is not their problem.
"But you need to be sharp when you are offensive and creative.”
Kane will lead Tottenham's line in the north London derby this afternoon and Pochettino is adamant the striker will deliver, despite his failure to convert a couple of chances at Upton Park.
“Against West Ham, Harry had two or three clear chances to score.
"I have full confidence in him. Sometimes, there is a period in which it is difficult to score. He is not a machine."
Kane, meanwhile, has shrugged off any suggestion that the mask plays on his mind during a game.
“Once you start playing, you kind of forget it is on. It’s all good,” he insisted.
