Novak Djokovic has welcomed the International Tennis Federation's (ITF) decision to delay the start of matches until 3:00pm (local time) at the Tokyo Olympics on Thursday.

The world number one has cruised through to the quarter-finals, where he will meet home favourite Kei Nishikori, but he – along with many others – had complained of heat and humidity causing problems due to contests starting too early.

That decision has come after world number two Daniil Medvedev struggled with conditions as he was forced to use two medical timeouts on Wednesday to cope with the heat and subsequently asked chair umpire Carlos Ramos, per ESPN, "If I die, are you going to be responsible?"

The pushback now means the majority of the games in the closing stages will be played in slightly cooler conditions in order to protect player welfare amid growing health concerns.

Speaking after a 6-3 6-4 mixed doubles win with Nina Stojanovic against Brazil's Luisa Stefani and Marcelo Melo, the Serbian expressed gratitude for the ITF's decision, though he felt it should have come earlier.

"It was nice news to receive," Djokovic said. "It's better than starting at 11:00am. It's not just in my opinion. I've spoken to six out of eight quarter-finalists in men's singles and everyone is in favour of starting later because the conditions are really brutal.

"It's very good [news] because you don't want to see situations like what we saw today with Paula Badosa [who retired after the first set].

"I've played tennis now professionally for 20 years, and I've never faced these kind of conditions in my entire life on a consecutive daily basis.

"I did experience certain similar days, one day in Miami or New York, or sometimes it happens here and there, but it's one or two days, and then it passes. Here is every single day. So, it's really draining players' energy, and you just don't feel yourself."

After gymnast Simone Biles' withdrawal to protect her mental health, Djokovic outlined the pressures that come with professional sport, too.

"Pressure is a privilege, my friend. Without pressure, there is no professional sport," he continued.

"If you are aiming to be at the top of the game, you better start learning how to deal with pressure and how to cope with those moments on the court, but also off the court.

"I've developed the mechanism on how to deal with it in such a way that it will not pose a distraction to me. It will not wear me down. I feel I have enough experience to know myself how to step on the court and play my best tennis.”

Djokovic, who was unsure if he had ever played in an "official" mixed doubles competition, and Stojanovic will now face Germany's Laura Siegemund and Kevin Krawietz in the quarter-final.

Despite limited experience, the six-time Wimbledon winner enjoyed the outing and was surprised how quickly he and Stojanovic understood each other's games.

"We did not chat about the tactics too much," the 34-year-old added. "We know each other, but we've never really played in the opposite ends of the net, or the same side of the net, so it was amazing how well we clicked from the beginning."