Alan Hutton insists Roy Keane's "volcanic" personality has been key to Aston Villa's impressive start.

The defender believes the Villa assistant has added fire to the dressing room after his summer arrival.

Villa are second in the Barclays Premier League and host Arsenal on Saturday after opening their campaign with four unbeaten games.

And right-back Hutton, who signed a three-year deal at the club this week, said Keane's famous passion is vital.

"He can be occasionally volcanic, is that threat useful? I think so, it keeps you on your toes, but you want to perform for yourself," he said.

"You know he'll give you the shot you need to perform and spur you on, it's not a negative thing.

"You just have to look at his career, if there's anything you need to ask he's the man to go to. Just to have a man like that in your corner is unbelievable.

"He's passionate about the game, so if anyone needs to say anything about the game he's the man to do it."

Former Manchester United midfielder Keane arrived in July as Paul Lambert's assistant and has also continued in his role as Martin O'Neill's Republic of Ireland No.2.

Lambert and Keane had not previously worked together but have been long-term friends and Hutton believes that has helped them to quickly develop a close relationship.

"They have worked unbelievably well together – everything has worked and clicked – I don't see why we can't go from strength to strength in the future," he said.

"Roy's done brilliantly for everyone – he's lifted the standard in training and he'll let you know if that standard drops.

"Though there's no doubt who's number one. Everyone knows who the manager is and no one has ever questioned that."