Well if you’re asking 
He’s Mikhail Youzhny, the second most successful Russian male tennis player of all time, who retired a month ago. The picture of him is of him doing his “salute” which he started doing as a tribute to his dad who was in the army. Nicknamed “The Colonel” he was also best known for on more than one occasion battering his own head with his racquet and drawing blood.
In short one of those slightly mental also-rans that us tennis fans tend to get a soft spot for.