London (AFP) - Defending champion Andy Murray will retain his world No. 1 ranking if he makes the Wimbledon semi-finals Wednesday, while Roger Federer defies age and Novak Djokovic fights a shoulder injury.
Adding extra spice to Wednesday's drama is a growing concern over the state of the All England Club's famed Centre Court where, according to Djokovic, a hole has developed.
Murray, one of five men over 30 in the last-eight, faces big-serving Sam Querrey bidding to make his eighth Wimbledon semi-final in the last nine years.
The Scot is also in his 10th straight quarter-final at the tournament and has reached the last-eight at 24 of the last 26 Slams. He leads Querrey 7-1 with the 29-year-old American's only win coming in Los Angeles seven years ago.
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Murray also won their previous clash at Wimbledon in the fourth round in straight sets in 2010. But the two-time champion will not underestimate the player who knocked out Djokovic in the third round 12 months ago.
"Sam likes the conditions here. Obviously a big serve. Goes for his shots. Very aggressive player," said Murray.
Querrey, the world No. 28, will attempt to become the first American in the semi-finals since Andy Roddick finished runner-up in 2009.
Federer, playing his 100th match at the All England Club, attempts to reach his 12th Wimbledon semi-final and stay on course for a record eighth title when he faces Raonic.
However, the 35-year-old Swiss star is wary of the sixth-seeded Canadian who knocked him out in the semi-finals in 2016.
Federer leads Raonic 9-3 in head-to-head meetings and has reached his 50th Grand Slam quarter-final without dropping a set.
"I can look at this quarter-final in a totally relaxed fashion. Physically I'm not fighting anything like last year with my knee," added Federer, bidding to become the tournament's oldest champion in the Open era.
Djokovic takes a staggering 25-2 career record over Czech 11th seed Tomas Berdych into his quarter-final as he eyes a potential semi-final duel with Federer.
The second seed needed a medical timeout to treat a long-standing right shoulder injury in his last-16 clash with Adrian Mannarino.
Berdych has not defeated Djokovic since 2013 but he did triumph over the Serb at Wimbledon in the semi-finals seven years ago when the Czech finished runner-up to Nadal.
In the day's other tie, 34-year-old Gilles Muller makes his maiden appearance in the last-eight after knocking out Nadal, his first win over a top five player in 23 attempts.
The Luxembourg player's only other Grand Slam quarter-final came in 2008 when he lost to Federer at the US Open.
He trails last-eight opponent Marin Cilic 2-0 but he has been in fine form on grass this summer, winning the title at 's-Hertogenbosch and reaching the semi-finals at Queen's where he lost to Cilic.
Cilic, the 2014 US Open champion, is in the quarter-finals for a fourth successive year.