Dan Evans beats Grigor Dimitrov at the Citi Open in Washington

Dan Evans produced a straight-sets victory over 12th seed Grigor Dimitrov to advance to the last 16 of the Citi Open in Washington.

The British No 4 was at the top of his game throughout to set up a date with either Lukas Lacko or Jack Sock for a place in the quarter-finals after a 6-4 6-4 win over the Bulgarian.

Evans had three match points to close out the contest at 5-2 in the second set but Dimitrov saved all three before breaking the Briton's serve and then holding his own.

However, Evans held his nerve when serving for the match for a second time and converted his fifth match point to secure the victory.

Meanwhile, Sam Querrey made a triumphant start to his first event since stunning top-ranked Novak Djokovic at Wimbledon.

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The 28-year-old rallied to beat American compatriot Bjorn Fratangelo 6-7 (5-7) 6-4 6-4 and avenged a first-round French Open loss in May.

"Even without the Novak win, it would have been tough," Querrey said. "It was one of those matches you have to fight through and I'm happy I fought through the way I did."

Querrey downed Djokovic in the third round on the Wimbledon grass, ending the Serb's 30-match major win streak on his way to his first career Grand Slam quarter-final after 10 years of trying, where he lost to Canada's Milos Raonic.