In 2013 he achieved one of the great shocks in tennis history, knocking defending champion Roger Federer out of Wimbledon. Today, the Ukranian player Sergiy Stakhovsky is a volunteer fighter on a military patrol in Kyiv, which he vows to defend "to the end" against Russian forces. It's been just over two weeks since he returned to Ukraine and signed up for the territorial brigade, the volunteers tasked with helping the army against the Russian invasion launched on February 24. "I knew I had to go there", he tells AFP. IMAGES AND SOUNDBITES