Tomic guns down Dolgopolov

Bernard Tomic knocked out fourth seed Alexandr Dolgopolov to reach the quarter-finals of the Memphis Open.

The 22-year-old Australian saw off his Ukrainian opponent 6-1 7-5 in 66 minutes to set up a clash against Donald Young, one of five Americans to make the last eight.

Young defeated compatriot Denis Kudla 7-5 6-3 to make sure of a first appearance in the quarter-finals of this event since he made his debut in it in 2008.

Sixth seed Steve Johnson won a see-saw encounter with Dustin Brown 4-6 7-5 7-6 (7/3) in two hours.

Next up for him will be second seed Kevin Anderson, who became the fifth and final American to book his place in the quarter-finals with a 6-3 6-2 win over Sam Groth in a match which lasted a little under an hour.