Roger Federer has had to contend with a serious right knee injury in the past two years. The former world number 1 played just 13 official matches in 2021, collecting nine wins and four losses. The round of 16 at Roland Garros and the quarterfinals at Wimbledon were his best seasonal results, a far too meager booty for a legend of his caliber.A few weeks after the Championships, the King announced that he had suffered a knee relapse and had to operate for the third time in 18 months. The 20-time Grand Slam champion hopes to be back in action at the end of the summer or early autumn, perhaps for the Laver Cup (which will take place at the O2 Arena in London at the end of September).The Swiss champion had to over …