BELGRADE (Reuters) – World number one Novak Djokovic, Austrian Dominic Thiem and Germany’s Alexander Zverev won their opening Adria Tour matches in contrasting fashion as the two-day charity event got underway on Saturday.

The tournament, organised by Djokovic while international tennis remains suspended due to the COVID-19 pandemic, has adopted a more streamlined format than what is seen on the main tours.

Sets are slashed to best of seven games, with eight players competing in two pools on a round-robin basis.

Djokovic made light work of his 4-1 4-1 win over compatriot Viktor Troicki in Group A while Thiem was leading against Damir Dzumhur 2-0 in the opening set when the Bosnian retired with a thigh injury.

During his clash with Troicki which at times resembled a training session more than it did a competitive match, Djokovic exchanged a few shots with a young boy from his academy and was delighted with the festive atmosphere.

“I really enjoyed myself out there,” Djokovic said in a courtside interview in front of a capacity 4,000 crowd who thronged the Serb’s tennis complex by the Danube river.

“Viktor started well but he seemed to have lost his momentum after the opening few games and in this format the match can be over pretty quickly.

“Once again I want to thank every player who turned up and all the fans who flocked in, their presence has made this weekend a memorable one.’

The afternoon session’s opening clash in Group B was the most entertaining as Bulgarian Grigor Dimitrov beat home favourite Dusan Lajovic 4-3 3-4 4-3, with all three sets decided by tiebreaks.

Zverev looked out of sorts in the opening set against Filip Krajinovic but recovered to produce his best shots in the third set for a 0-4 4-3 4-3 victory.

In the evening session, Djokovic clashes with Krajinovic and Zverev takes on Troicki in Group A while Thiem plays Lajovic and Dimitrov locks horns with Nikola Milojeic, who was drafted in as a replacement for Dzumhur, in Group B.

The group winners, to be decided after Sunday’s round-robin matches, will meet in the final.