Boris Becker believes Andy Murray is feeling less pressure and is in a position to challenge Novak Djokovic for superiority at the top of men's tennis.
Having been defeated by Djokovic in each of the first two majors of 2016 at the Australian Open and French Open, Murray has taken full advantage of the world number one's recent struggles by winning a third grand slam title at Wimbledon and his second Olympic gold medal at Rio 2016.
Murray will aim for a second US Open crown at Flushing Meadows in the final slam of the year, the Briton starting his campaign against Lukas Rosol on Tuesday a day after Djokovic begins his title defence versus Jerzy Janowicz.
And Djokovic's coach Becker wrote in his column for gulfnews.com: "The year 2016 seems to have been a bit of a change-of-guard type of year for men's tennis.
"With Roger Federer missing out on Paris and New York and Rafael Nadal also grappling with fitness issues, the 'Big Four' of tennis seems to have been reduced to the 'Big Two' with Novak Djokovic and Andy Murray really developing a great rivalry.
"I really can't put a finger on what has changed for Murray as he always had a complete game and some amazing strengths as far as his groundstrokes are concerned.
"What I think has changed for Murray is that a maturity and stability has come into his life. The first big watershed was the London Olympics followed by the US Open win in 2012.
"However, he has not won as many grand slams as he would have liked since 2013. This Wimbledon and Olympic gold shows that he is now less pressured and more in control of the mental side of things.
"I see him really challenging Djokovic's supremacy in the next few grand slams."