Roy Keane says Ireland will need to be wary of Eden Hazard when they meet Belgium in Saturday's European Championship match, despite the winger's disappointing season with Chelsea.

Hazard endured a difficult start to the season, but improved his form dramatically towards the end of the campaign and racked up four goals in his last five league games.

"I don't know what's going on at club level with the guy but he's a talented boy," the Ireland assistant coach told reporters in France.

"But it does happen, players have dips in form. He's still an absolutely dangerous player and he showed a bit of better form before the end of the season for Chelsea. We'll have to keep an eye on him."

The 44-year-old former Manchester United captain has also been impressed by Belgium and United midfielder Marouane Fellaini, who made his bow at the European Championship in Belgium's 2-0 loss to Italy on Monday.

"I like him. I thought the criticism he had when he went to United was a bit over the top," Keane added.

Ireland, who opened their campaign with a 1-1 draw with Sweden, face Italy in their final group stage on June 22.