England scrum-half Ben Youngs believes Fiji centre Vereniki Goneva poses a huge threat to his team in Friday's Rugby World Cup opener at Twickenham.
Youngs, who is a team-mate of Goneva's at Leicester Tigers, is aware of the Fijian's qualities and knows England must be wary of him.
"Niki is one of the best players I've played with simply because he can either run over you or step you," he said.
"He makes you do the splits as you try to tackle him simple because you don't know what way he will try to go.
"He's got all the ability, great hands and is a physical guy. He can be very physical, but also subtle with electric pace.
"He has the balance of both types of game and is one of many for Fiji."
But Youngs, who will win his 50th cap for England on Friday, is confident his team can keep players like Goneva and giant wing Nemani Nadolo in check.
"Fiji are a little bit of the unknown because they can do the unexpected," he added.
"There's only so much prep we can do on them because they can do something out of nothing, that's the type of player they have.
"We'll have to make sure we're watertight in defence and force them to make errors and play too loose."