As tennis recovers from players' doping drug tests, Edmund Willison, Jannik Schneider and Simon Briggs report on mentors with tainted backgrounds

After the recent news that two high-profile players will miss today’s Australian Open after testing positive for banned steroids, an urgent question hangs over this showpiece event. Does tennis have a doping problem?

This week in Melbourne, The Daily Telegraph spoke to leading players about the positive tests of world No 78 Nicolas Jarry and reigning Wimbledon doubles champion Robert Farah. We encountered a widespread belief that both men would be exonerated, having suffered from cross-contamination.

“I can’t imagine these guys are dopers,” said world No 5 Dominic Thiem. “It is ridiculous and is completely made up, for us. It’s a mistake in the system.”

Yet there is proof that doping exists in the sport. Players test positive and former players who served doping bans still work in the game.

The Telegraph can reveal that Martin Rodriguez – who is Nicolas Jarry’s uncle-in-law, and was also his coach until October last year – committed an anti-doping rule violation during his own career. At the turn of the century, he was part of a group of players who left Argentinian tennis fighting for credibility.