Belgrade, June 26 : Manchester United midfielder Nemanja Matic expressed solidarity with his compatriot and tennis world no.1 Novak Djokovic, who has been under fire in recent days for his Adria World Tour and the spurt of coronavirus cases because of it. The Serbian international said that Djokovic should have never apologised for hosting the tournament and that "mice" around the world have now come "out of their hole" to criticise him. "Mice came out of the hole and gave themselves the right to criticise the world number one, in tennis but also how he relates to all other people in the world," Matic wrote in an open letter in support of Djokovic published by Serbian media. "But I don't care. Very soon the cat (Djokovic) will be on the court, and the mice in the hole. "The only thing for which I resent Novak is that he apologises to the mice who criticise him for no reason. No, Nole. They will apologise to you -- soon." Matic also said that the Belgrade leg of the tour did not break any rules of the land in relation to coronavirus. The tour was set to consist of tournaments in cities accross Baltic countries and was played in Belgrade and Zadar, Croatia. Social distancing rules had been relaxed in the countries and the matches featured packed stadiums and there were videos of the players partying over the course of the tour. It was towards the end of the Croatian leg that the coronavirus cases started to come up among those that participated in the tournaments and it was eventually called off. Djokovic and his wife themselves tested positive for the virus and the Serbian apologised in a statement. "I am so deeply sorry our tournament has caused harm. Everything the organisers and I did the past month, we did with a pure heart and sincere intentions," Djokovic said. "We believed the tournament met all health protocols and the health of our region seemed in good condition to finally unite people for philanthropic reasons. We were wrong and it was too soon. I can't express enough how sorry I am for this and every case of infection," he added. /IANS