Jo-Wilfried Tsonga has suggested that Andy Murray is losing his fear factor after struggling to maintain the form that crowned him Wimbledon champion last year.

The Scotsman has failed to win silverware since his history-making victory at the All England Club, and has also not beaten a top 10 player since last year's Wimbledon tournament.

Tsonga, who ended a six-year losing run against Murray in Toronto this season, will go up against the British number one at Flushing Meadows today in the US Open fourth round.

"The locker room is maybe a bit less afraid of Andy because he's losing a few more matches than in the past, but I don't know any player who once on court is going to be super-confident against Andy," BBC Sport quotes Tsonga as saying.

"He's different than in the past maybe because I feel he's not serving as strong as he used to, nor maybe hitting as strong as he used to."

The winner of the encounter could face Novak Djokovic in the final eight.