Murray begins his Wimbledon preparations this week as he defends his title in the grass-court tournament at Queen's Club.
Murray begins his Wimbledon preparations this week as he defends his title in the grass-court tournament at Queen's Club and American legend McEnroe may have given the Scot a little extra motivation with his criticism.
Although Wimbledon champion Murray remains top of the rankings, the 30-year-old has struggled this year, while Nadal and Federer have enjoyed unexpected revivals.
At Wimbledon, Federer will be hoping to clinch a 19th Grand Slam, while Nadal and Djokovic are gunning for their 16th and 13th respectively.
McEnroe told the Sunday Times that Murray, who has won three major titles, can't be ranked on the same level as his 'Big Four' rivals.
But while the Scot admits that rings true for their whole careers, he pointed to his record at the Olympics, where he has won two singles gold medals, as evidence to the contrary.
"For me, it doesn't matter what anyone else thinks. I'm very proud of the Olympic medals, they mean a lot to me," Murray said at Queen's Club on Sunday.
"Within tennis, a lot of people just go 'oh that guy was a better player because he won more Grand Slams than that one or that woman was better because she won more Grand Slams'."
"If that's the case then what is the point in all of us being here today? Why is everyone here covering this event? There are other tournaments outside the slams as well."
"If you look at the titles and everything those guys have won, I can't compare myself to them."
"There's maybe one or two things that I have done that they won't have but for the most part I would have been fourth."
"But it's not true of the last year because I'm ranked number one in the world. I've been better than them for the last 12 months, that's how the ranking systems work."
Murray also stood by his recent claim that he may only have two or three more years left challenging for major honours, despite Federer winning the Australian Open aged 35 in January.
"It's really hard, it's always tough to stay at the top of any sport," Murray said.
"I hope I stay at the top of the game for five, six, seven years but I think just because Roger's done it doesn't mean that's going to happen to everyone."
"Right now, I feel good, but we'll have to see how I am."
Murray will face British number four Aljaz Bedene at Queen's on Tuesday as he looks to hold onto the title he won for a record fifth time last year.