Novak Djokovic has confirmed that Alexander Zverev will play Adria Tour and revealed why Roger Federer and Rafael Nadal won't.

The 17-time Grand Slam champion has organised the tournament for the Balkan region with the first matches scheduled for 13 June before the event draws to a conclusion on 5 July.

Three-time Grand Slam finalist and world No 3 Dominic Thiem as well as world No 19 Grigor Dimitrov were last week confirmed for the tournament and Djokovic has added the name of Zverev to the list.

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"I am delighted that Dominic Thiem, Grigor Dimitrov and Alexander Zverev will be my guests here in my hometown," the world No 1 said.

"This is the first time any of them will be playing here and I will do everything in my power to be a good host."

When asked why Federer and Nadal were not invited, Djokovic replied: "Quite frankly, inviting Federer didn’t cross my mind because... he is still nursing a knee injury.

"As for Nadal, I have no problem giving him a call but I wouldn't expect him to come over."

Belgrade will host the first leg on 13 and 14 June before they move to the coastal resort of Zadar in Croatia on 20 and 21 June.

There are still doubts over whether or not Montenegro and Bosnia will be able to host the final two legs.

"Bosnia and Montenegro are still not 100% certain as the hosts of the final two legs because we haven't had enough time to prepare the infrastructure, but we are very nearly there," the Serb said.

"As for the three big names coming over, they will all play in the opening leg in Belgrade. Zverev might play in Croatia too while Dimitrov could appear in Croatia and in Montenegro."

- TEAMtalk media