BELGRADE, Serbia—Viktor Troicki clinched Serbia's first Davis Cup championship three years ago, but is banned from attending this weekend's Davis Cup final as he serves a 12-month suspension for a doping violation.

Though Troicki is a missing man, Novak Djokovic says his friend and former teammate remains a positive presence for the Serbian team.

Djokovic, who staked Serbia to a 1-0 lead over the visiting Czech Republic with a three-set win over Radek Stepanek today, reiterated his support for Troicki after the match. Djokovic also said he has no plans to call the World Anti-Doping Agency chief, who questioned Djokovic's knowledge of the testing process.

"I am not going to call [WADA president John Fahey] because I know more than he thinks I know," Djokovic said in today's post-match press conference. "So for me this is a total injustice. It shows again the system does not work and there is nothing that they can say to convince me [that it does]."

Fahey suggested Djokovic was uninformed after the six-time Grand Slam champion criticized the Court of Arbitration for Sport for its failure to repeal Troicki's suspension.

“I don’t think Novak Djokovic has the faintest idea what we do and if he wants to understand what we do I’m more than happy to pick up the phone and talk to him, if he wants to talk to me,” Fahey told CNN. "If he wishes to then make a comment I might listen to him but for the moment I don’t think that was an informed statement.”

Djokovic, who staunchly defended Troicki at the ATP World Tour Finals last week, said he spoke to Troicki before today's opening match.

"I saw him before the match and he wished his best," Djokovic said. "And we feel his presence. Even though he’s not with us here in the arena we know he’s cheering and trying to give us positive energy."