New Delhi, March 20 : While the ICC World Test Championship rankings were modified keeping in mind Covid-19 restrictions that couldn't see some of the series get underway last year, the ATP's 'covid protection ranking' in tennis has created controversy. According to the new system, the rankings have been frozen in the wake of Covid-19 pandemic allowing players to not play and retain their ranks. German Tennis Federation vice-president Dirk Hordorff has pointed out at the discrepancy saying that the big four deciding their schedule suiting themselves, and thereby managing to protect their rankings, is affecting others like Alexander Zverev and Andrey Rublev, who are winning but not climbing in rankings. The big four of tennis comprise Roger Federer, Rafael Nadal, Novak Djokovic and Andy Murray. "Some of you have problems to understand the ranking system of the ATP, but it's so easy," Hordorff wrote on his Facebook page. "Roger Federer can choose his ranking place, even without playing. Rafa Nadal is happy to get a ranking system with three years keeping the points," added Hordorff and pointed out sarcastically that both Federer and Nadal are player council members. "Novak Djokovic is ranked one and the best player, so he doesn't care who is behind him and what the player council decides. He is happy." "Murray doesn't win. He gets wild cards. And as long as he is not winning and getting wild cards, he doesn't need to climb. And who cares about the rest." Hordorff said Zverev and Rublev are upset at it. "Daniil Medvedev is two in the ranking, but nobody really knows this. Alex Zverev and Andrey Rublev are p****d that they are winning but don't climb in rankings," he said. The ATP had earlier announced plans to protect the rankings of players who may be unable to play due to ongoing Covid-19 restrictions. It means that the top players like Djokovic, Nadal, Federer as well as others can pick and choose tournaments and still retain their rankings. Besides this, there already exists the 'Best Of' system, which allows players to keep their best result from either the 2019 or 2020 events. /IANS