Andy Murray beats John Isner at Shanghai Masters

Andy Murray beat John Isner in the Davis Cup first round in Glasgow in March

Andy Murray came from a set down to beat John Isner and reach the quarter-finals of the Shanghai Masters.

The British world number two, 28, showed excellent resilience in the face of the American's powerful serving to win 6-7 (4-7) 6-4 6-4.

Murray got the decisive break in the seventh game of the final set before serving out to seal victory after two hours and 31 minutes in China.

He will face Czech Tomas Berdych in the last eight on Friday.

"Your patience is certainly tested when you play against guys like John," Murray told Sky Sports.

"It's always tough against him - you can feel like you have control when you are into rallies but it's tough to get into them sometimes,"

Murray has won all five meetings with the 30-year-old 13th seed.

Serve was dominant in the opening set, with neither player forcing a break point and a tie-break was an almost inevitable conclusion.

Isner took it after claiming the decisive mini-break when leading 2-1, a superb drop shot catching Murray on his heels following a series of powerful forehands from the American.

Both players had chances when receiving in the second set and it was Murray who finally made the breakthrough at 4-4, a backhand down the line converting his seventh break point.

Even then he had to face two break-back points when serving for the set, with drop shots and clever second serves helping him to the level the match.

Murray continued to dominate in the final set but the American saved four more break points until a lob over the 6ft 10in Isner helped the Scot move ahead.

After missing a match point at 5-3, Murray than faced a break-back point as he served for the match but the American went wide with his return as Murray sealed victory.

Murray 'positive' on Mauresmo return

Murray is hoping coach Amelie Mauresmo will return to his team for the start of the 2016 season after a "positive" telephone conversation with the Frenchwoman.

Mauresmo has been absent from his support staff since Wimbledon, having given birth to her first child in August, with Swede Jonas Bjorkman taking on the main coaching duties.

Murray said Mauresmo "has gone away to think about" their future, adding: "I think she wants to continue doing it. It obviously has to work for both, but I'm pretty positive about it."

No fine for Kyrgios

Meanwhile, Nick Kyrgios will not be fined by the ATP despite being given a code violation for unsportsmanlike conduct during his second-round defeat by Kei Nishikori.

The Australian, 20, smashed away a loose ball and nearly hit a linesman after losing the second set on Wednesday.

Kyrgios was fined $1,500 (£984) on Tuesday after calling the tournament a "circus" and complaining about the ball kids during his first-round win over Andreas Haider-Maurer.