World No. 1 and four-time champion Novak Djokovic made a splash ahead of the Dubai Duty Free Tennis Championships on Friday as he took some time out from practice to enjoy an afternoon at the Wild Wadi Waterpark in Dubai.

The Serb was joined by his brother, Marko, and friends as they enjoyed some underwater fun and many of the water rides at the park, including Tantrum Alley and Burj Surj.

Earlier, Djokovic had visited Bab Al Yam restaurant at Burj Al Arab, where he was greeted by Chef Maxime Luvara, who helped the Belgrade native create his very own juice.

Djokovic is set to return to action for the first time since defeating Andy Murray in the Australian Open final last month. The Serb is chasing his fifth title at this ATP World Tour 500 hard-court tournament, having lifted the trophy in 2009 (d. Ferrer), 2010 (d. Youzhny), 2011 (d. Federer) and 2013 (d. Berdych). Last year he finished runner-up to Roger Federer.

Main draw play is set to begin on Monday in Dubai. Djokovic is joined in the strong field by Stan Wawrinka, Tomas Berdych and Feliciano Lopez, as well as stars of the Next Generation, Nick Kyrgios and Borna Coric.

Fourth seed Marin Cilic reached his first semi-final of the season as he defeated Andrey Kuznetsov 6-3, 6-4 on Friday at the Open 13 in Marseille.

The Croatian improved to a 3-0 FedEx ATP Head2Head lead over Kuznetsov as he fired 10 aces and won 81 per cent of his service points, claiming victory in just 66 minutes. The 24-year-old Kuznetsov was bidding to reach his first ATP World Tour semi-final and fell to a 0-7 mark in quarter-finals. He also missed out in the Doha quarter-finals in the first week of the season (l. to Nadal).

The 27-year-old Cilic is looking to reach the final of this ATP World Tour 250 indoor hard-court tournament for the second time, having finished runner-up on his last appearance in 2011 (l. to Soderling). The right-hander goes on to face either top seed Stan Wawrinka or Benoit Paire.

Nick Kyrgios hit top form as he stunned third seed Richard Gasquet 6-0, 6-4 in less than an hour to reach the semi-finals. In a dominant display, the 20-year-old Australian relinquished just six points on serve and fired 17 aces, breaking Gasquet three times from seven opportunities in the pair’s sixth meeting.

It was just Kyrgios’ second win over Gasquet, whom he also defeated 10-8 in the fifth set in the 2014 Wimbledon second round. The Canberra native will bid to reach his second ATP World Tour final when he faces either Tomas Berdych or David Goffin on Saturday. Kyrgios reached his maiden final last year in Estoril, finishing runner-up to Gasquet.

Everyone in Delray Beach was rooting for Juan Martin del Potro, even his next opponent.

“I was really happy for him to come back,” said Jeremy Chardy, whom the Argentine will meet in the quarter-finals of the Delray Beach Open. “For a tennis player, the worst is to be injured. [His comeback] is great for the fans too. We need players like him on the tour.”

Del Potro downed Aussie John-Patrick Smith 6-4 6-4 during Thursday’s night session in 77 minutes to set up a third meeting against Chardy (1-1), who eased past American Noah Rubin 6-4, 6-2.

“Physically I felt good,” del Potro said after his match. “But I was playing too many slices. It’s not my game. If I improve my backhand, I will once again be the Tower of Tandil.

“I am so happy to be here, playing in front of my fans. If I can play better, next year I will be back for sure.”

Chardy will be hard-pressed to handle del Potro’s power, but he was glad to see his close friend continue his comeback bid.

“I know [del Potro] really well,” Chardy said. “He’s one year younger than me so we’ve known each other since we were kids. He’s a good friend of mine. We had a lot of fun in juniors together. We never missed a Players Party [back then].

Tim Smyczek was down a set and a break to fellow American Donald Young, but rallied 1-6, 7-6(2), 6-2 to reach his second ATP World Tour quarter-final (2011 San Jose).

“I was trying to figure out how to disrupt what he was doing,” Smyczek said. “My game plan wasn’t bothering him so I had to do something different. I stopped being so offensive. [Young] does very well when he’s under pressure so I had to turn the tables a bit.

“Because we’ve played each other so often in the past, I had to do some things which weren’t my forte. Same for him, which was interesting. I am happy I fought my way through.”

His standing as the King of Clay is undisputed, but on Thursday top seed Rafael Nadal had to grind his way past another of the ATP World Tour’s most dominant clay-courters, Nicolas Almagro, at the Rio Open. In the battle of the Spaniards, Nadal steadied to hold off the former World No. 9 6-3, 7-5 to reach the quarter-finals of the tournament he won in 2014.

Nadal brought a dominant 347-31 record on clay into his second-round match – clearly the best among active players – while Almagro arrived with a 262-129 mark, the third best on tour. Almagro, though, would have to win just his second FedEx ATP Head2Head clash with his 29-year-old countryman, having won just four of the 36 sets played between the two in 14 previous encounters.

Nadal drew first blood, breaking for 3-1 in the opening set. He recovered from 0-40 while serving for the set to take it after 43 minutes. In the second set, the World No. 5 in the Emirates ATP Rankings had the chance to serve out the match after breaking to love for 5-4.

With the finish line in sight, however, Nadal wavered. He dropped serve before breaking Almagro again in what was the fifth straight break of serve between them. Serving for the match for a second time, Nadal made no mistake. He closed it out on his first match point in one hour and 41 minutes to book a rematch of his 2014 final against Ukraine’s Alexandr Dolgopolov.