Every time I write him off I get proven wrong. I thought he'd never win a slam off clay or become world number one; he broke that by ending Fed's ridiculous Wimbledon streak in that '08 epic and became number one shortly thereafter. I thought he'd never win all the majors; he proceeded to win the career slam and has multiple titles on each surface. I thought Djokovic had owned him for good in 2011/12; proceeds to win the next 4 slam matches against Novak following the AO '12 epic. I thought his knees would force him into either a retirement or gross decline in 2012; he came back to dominate in 2013 and he beat Djokovic to RG, USO and YE N1. I thought his career was flat out over in 2015/16; then 2017 happens. I thought father time was beginning to defeat him at last in late 2018/early 2019, then he proceeds to win 2 majors and become world number one again. As someone said above, he might actually has more lives than a cat.