Andy Murray wary of Denis Istomin

World number three Andy Murray has admitted that winning against Uzbekistan's Denis Istomin in the fourth round of the US Open on Tuesday will not be easy.

The Briton defeated the 26-year-old in the quarter-finals of the Brisbane International back in January of this year.

"Technically he's very sound," BBC Sport quotes Murray as saying. "He's a good player.

"He hits the ball very flat. He had a very good match with Novak [Djokovic] in Montreal. He's had some good wins this week, as well."

Istomin has reached the fourth round of a Grand Slam only once before.