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Top-seeded world No. 1 Novak Djokovic is trying to extend his record to nine titles in Melbourne, but an injury and No. 6 seed Alexander Zverev stand in the way when the two square off in the 2021 Australian Open quarterfinals at 4:15 a.m. ET on Tuesday. Djokovic has won 17 Grand Slam events and has his sights on matching the 20 of Roger Federer and Rafael Nadal. He looked strong in a 7-6(4), 4-6, 6-1, 6-4 victory against Milos Raonic.

Zverev eased past 23rd-seeded Dusan Lajovic 6-4, 7-6(5), 6-3 on Sunday and gave Djokovic a run for his money in a three-set loss at the ATP Cup less than two weeks ago. The latest Djokovic vs. Zverev odds from William Hill Sportsbook list Djokovic as a -200 favorite (risk $200 to win $100) to win the match outright, while  Zverev is going off at +160 (risk $100 to win $160). There are a variety of other Djokovic vs. Zverev picks on the board like total games, with the over-under set at 41.5. Before making any Djokovic vs. Zverev picks, be sure to see the 2021 Australian Open predictions from famed tennis handicapper Sean Calvert.

Calvert is the famed handicapper who called Stan Wawrinka winning the 2014 Australian Open at 60-1, the last Australian title won by someone other than Djokovic or Roger Federer. In 2019, Calvert took down a huge score on Dominic Thiem winning Indian Wells at 80-1, among many stunning calls. Anyone following his picks is way up.

Now, Calvert has scrutinized the latest Australian Open 2021 odds and released his coveted best bets. He's sharing all his picks and analysis at SportsLine.

Djokovic vs. Zverev preview

Calvert's mind was eased by how Djokovic played in his matchup with Raonic. The 33-year-old served and moved well during the match, and Calvert believes his talk of withdrawal and long-term concerns might be overblown. Djokovic's return game remains among the best in tennis and he won the title here the past two years.

Djokovic dropped the first set in his last meeting with Zverev, but he found the right positioning against the German's high-powered second serves. Zverev's aggressive approach was costly, with double faults giving Djokovic the opening he needed to get his fourth straight win against the 23-year-old. The Serb has won 32 percent of his return games over his career.

Zverev, on the other hand, made the semifinals in Australia a year ago and played tough against Djokovic in the match on this same surface in the ATP Cup. He has beaten Djokovic twice in seven tries and has held serve 94 percent of the time in Melbourne so far. The German is the world's seventh-ranked player and has a powerful serve that will test Djokovic's return prowess.

Djokovic's injury could play a factor, and the Serb said he might withdraw if it were any other event. Zverev hit 44 winners, including 15 aces, in his victory against Lajovic and is equally comfortable playing offense or defense. The 23-year-old lost in the U.S. Open final to Dominic Thiem in September after being up two sets, so he is motivated to keep it rolling in Melbourne.

How to make Djokovic vs. Zverev picks

Is Djokovic's injury enough to get Calvert to call for the upset? The tennis guru has released confident picks on the outright winner, as well as a play on how long this quarterfinal match lasts. Be sure to see Calvert's picks and analysis before locking in your Australian Open 2021 picks for the men's quarterfinals.

Who wins Zverev vs. Djokovic in the 2021 Australian Open men's quarterfinal? And what pick could lead to a big return? Visit SportsLine now to see Sean Calvert's best bets for Zverev vs, Djokovic, all from the famed tennis handicapper who called Stan Wawrinka winning the 2014 Australian Open at 60-1.