Karim Hossam was one of the best young tennis players in the world. He looked set to play at the biggest tournaments, with the top players of the game. Instead he was sucked into one of the biggest match-fixing rings yet discovered in a sport riddled with corruption. The BBC's Simon Cox and Paul Grant use confidential documents to tell the story of his downfall. It was inside a modest hotel room in Tunisia in June 2017 that Karim Hossam's tennis career started to unravel. Across from the 24-year-old sat two former British police detectives. They were investigators for the Tennis Integrity Unit, which probes corruption within the game, and they suspected Karim had been fixing matches. In a series of interviews over six months he revealed how four years earlier he had become a part of one of the biggest match-fixing rings in tennis. The International Tennis Federation Futures tournament at Sharm el-Sheikh is a distant cousin to the glamour, money and crowds of Wimbledon or the French Open. Played at a small tennis club next to a shopping mall, there is a smattering of spectators and the prize money for the whole tournament is $15,000 (£11,500) - about a quarter of the sum made by a first-round loser at Wimbledon. Karim Hossam had already won the tournament four times when he arrived to compete there again in 2013. Still only 20, the young Egyptian player was the great hope for North African tennis.