NEW YORK: Wimbledon champion Andy Murray battled past energetic Italian journeyman Paolo Lorenzi 7-6 (7/4), 5-7, 6-2, 6-3 on Saturday to reach the last 16 at the US Open.

Sloppy and out of sorts in the early going, Murray had all he could handle from the 34-year-old Lorenzi, but worked his way through to a meeting with Bulgarian Grigor Dimitrov, a 6-4, 6-1, 3-6, 6-2 winner over Portugal´s Joao Sousa.

Lorenzi, who became the oldest first-time winner on the ATP tour when he lifted the trophy in Kitzbuehel in July, broke Murray for a 5-4 lead in the opening set -- just the second time the 2012 US Open champ dropped his serve this week.

He gave the break back with an error in the next game, and Murray eked out the tiebreaker to go forward one set up after one hour.

The two traded four breaks of serve in the second before Lorenzi finally sealed the set in the 12th game, when Murray sent another looping forehand long.

In the third, however, Murray was able to make his opening break of Lorenzi stand up, breaking him again for a 4-1 lead and finishing off the frame with an ace.

Looking more and more comfortable, Murray broke again to open the fourth, and after he fended off a break point in the next game the affair took on an air of inevitability.

But it was a closer call than expected for the second-ranked Scot, a three-time Grand Slam champion fresh off winning gold in the Rio Olympics, against the world number 40 who had never made it to the third round of a major before.

He had won just two Grand Slam singles matches in 13 years prior to this week. Murray said it wasn´t because he took Lorenzi lightly.

"I expected a tough match, I expected long rallies," he said. "I´m just disappointed with the amount of errors I made. I was quite impatient at times.

"When I did sort of play like I was planning on when I went out there, to be more patient, wait for the right balls to go for, I played much, much better.

"The unforced errors came down significantly and the winners went up. The third and fourth sets were comfortable."