London - John McEnroe reckons that Wimbledon remains the best chance Andy Murray has of beating World No 1 Novak Djokovic.Djokovic has been in imperious form over the last 12 months - almost unbeatable, in fact - as Murray found out in both the Australian and French Open finals.Murray's only success over Djokovic came in Rome in May, but when it comes to the really big matches, there's only been one winner.Three-time Wimbledon champion McEnroe, who was recently appointed as Milos Raonic's coach, says SW19 is Murray's best chance of defying the odds."In ways he's getting closer. I do think Wimbledon is his best chance," McEnroe said."If you were to say in terms of surface, I think he's best suited on grass and just having the crowd more on his side here at Wimbledon."So I think his best chance, not that he can't beat Djokovic at the US Open, he beat him in Rome not long ago, but his record has recently not been good."Murray is playing great, he's a great player, there's no question about it. But at the moment there's no question that the level Novak is at is something that you rarely, if ever, see."Murray recently rehired his former coach Ivan Lendl, and McEnroe says the Scot is clearly trying everything he can to gain an advantage."I think him adding Ivan, he's trying to get that little bit extra, just like other players are trying to do the same," McEnroe said."To me it's not surprising, it's not a no-brainer, but I think the fact his best success was with Ivan, it makes sense to give this another shot given the circumstances."It doesn't surprise me. I think it makes people think - if you get in someone's head in any way - whether that can make a difference, whether he makes a difference."