Playing Novak Djokovic at the Australian Open is one of the toughest challenges in tennis: Alexander Zverev

Novak Djokovic's favorite Grand Slam is, without a doubt, the Australian Open. The World No. 1 has triumphed at the year's first Slam a record-breaking eight times, while claiming he has a 'love affair' with the tournament.

With a ninth Australian Open title in sight, Novak Djokovic is through to the quarterfinals this year. But there remains some mystery around the exact status of his physical fitness ahead of his clash against Alexander Zverev on Tuesday for a spot in the semifinals.

Zverev on his part is aware of the difficulty of the task on his hands. The German, who is chasing his first Major, is looking forward to the match against Novak Djokovic - which he described as 'one of the toughest challenges' in the sport.

"You've got to play your best tennis, especially here," Alexander Zverev said. This is his [Djokovic's] favorite court, this is his favorite tournament. To be able to have a chance against him, you have to be playing extremely well."

"You have to be playing aggressive tennis, I think, being the one that dominates," the German added. "You know, I'm looking forward to the challenge. I think it's one of the toughest challenges in our sport to be playing Novak Djokovic this Grand Slam in later rounds."

"It's always a very physical match" - Alexander Zverev on his rivalry with Novak Djokovic

Alexander Zverev and Novak Djokovic

Alexander Zverev and Novak Djokovic have met on seven occasions in the past, with Djokovic leading the head-to-head 5-2. Djokovic has won their last four encounters, including their clash at the ATP Cup earlier this month which went right down to the wire.

With both players trying to dominate from the back court, their matches often turn into a physical battle, as the German pointed out.

"I mean, we played twice in the last few months, in London once and at the ATP Cup, which was an extremely close match, which could have gone both ways. I think he would say the same thing," Alexander Zverev said.

"But the other side, it's always a very physical match, always involves a lot of movement, I think. In a way you have to move extremely well against him," he added.

Alexander Zverev, the 2020 US Open finalist, also insisted he is satisfied with his own performance this fortnight. After dropping the first set in his first-round match, the German has won 12 consecutive sets to reach the quarter-finals.

"You know, I'm in the quarter-finals of a Grand Slam, so I've gotta to be doing something well," he said. "You know, I'm looking forward to what's ahead, the toughest matches I think are still ahead of me. I'm definitely looking forward to what's ahead."