BRITAIN’S Andy Murray admits he must capitalise on the chance to win grand slams when his rivals are not at their best.

Murray is yet to drop a set in his opening two rounds at the US Open and he faces Italy’s world number 40 Paolo Lorenzi today for a place in the last 16.

The Scot’s progress has been notable for its lack of drama, particularly while Novak Djokovic and Rafael Nadal both continue to wrestle with injuries at Flushing Meadows.

Nadal’s wrist problem appears less of an impediment than Djokovic’s right arm, which had the Serb taking treatment in round one and serving well below full strength.

Both players still came through comfortably, Djokovic with the help of a walkover in the second round, but questions remain about how they will hold up when tougher opponents arrive.

With Roger Federer absent from New York while he recovers from knee surgery, the stars look to be aligning for Murray as he seeks his fourth grand slam title and second here after lifting his first in 2012.

The 29-year-old, reunited with coach Ivan Lendl, has enjoyed the best year of his career so far, winning Wimbledon, the Olympics and reaching three out of three major finals.

“I have capitalised on a few opportunities,” Murray said. “When some of the other top guys maybe hadn’t played or struggled or lost, it’s important I have taken those chances when they have come my way.

“Becoming a parent has changed my perspective a bit on things. I feel a little bit calmer than maybe I did in my past about my tennis and how important tennis is in my life.

“It’s still extremely important, but it’s not the most important thing. And I think having Ivan back on my team has been great and has helped me a lot.”

Murray’s greatest obstacle may yet be the weight of expectation, given he is now considered the favourite in the draw, even with the likes of Stan Wawrinka and Juan Martin del Potro lurking in his half.

Fifth seed Milos Raonic, who beat Federer at Wimbledon before losing to Murray in the final, crashed out on Wednesday after admitting “nerves and stress” had left his body riddled with cramp.

Murray is one of the fittest players on tour, meticulous in his preparation, but he too experienced cramps here two years ago, when he survived a brutal contest with Robin Haase.

“The stress that you might put yourself under and the nerves that you feel can cause that,” Murray said. “I think most players have gone through it and for some reason it seems to happen more at this event.

“I don’t know if that is because of the humidity or maybe players are coming in here more fatigued at the end of a long season, a long stretch. I don’t know.”

Lorenzi is unlikely to instigate such problems, the 34-year-old a surprise winner of his own draining five-setter against Frenchman Gilles Simon on Thursday night.

This will be his first ever appearance in a grand slam third round.

“I’m feeling dead,” Lorenzi said after beating Simon. “I have one day off so I hope that on Saturday I will be full power again.”