Billed as the biggest boxing match of the century so far, Britain's Tyson Fury takes on Ukrainian star Oleksandr Usyk on Saturday with the winner of the fight set to be crowned the undisputed heavyweight champion of the world.

The much-anticipated showdown in Riyadh, Saudi Arabia, will see Fury will defend his WBC crown while Usyk will be placing his IBF, WBA and WBO titles on the line. 

The fight marks the first undisputed heavyweight title clash since 1999, and a win for Usyk would see him become the first fighter in history to win undisputed men's titles at both cruiserweight and heavyweight. 

A victory for Fury, meanwhile, would set up a long-awaited all-British showdown between the "Gypsy King" and Anthony Joshua.

Here are all the details of tonight's big fight, including start time, how to watch it and more.

Tyson Fury vs. Oleksandr Usyk date and start times

Tyson Fury vs. Oleksandr Usyk takes place on Saturday, May 18, at the the Kingdom Arena in Riyadh, Saudi Arabia. 

The main card is set to start at 12 p.m. ET or 9 a.m. PT in the US and Canada, making it a 5 p.m. BST start on Saturday afternoon in the UK, with the event set to get underway at 2 a.m. AEST in the early hours of Sunday morning in Australia. 

Ring walks for Fury and Usyk are expected no earlier than 6 p.m. ET, 3 p.m. PT, 11 p.m. BST and 8 a.m. AEST on Sunday.

Timing is subject to change for the main card based on the length of the undercard fights.

How to watch Tyson Fury vs. Oleksandr Usyk from anywhere

If you find yourself unable to view Fury vs. Usyk locally, you may need a different way to watch -- that's where using a VPN can come in handy. A VPN is also the best way to stop your ISP from throttling your speeds on game day by encrypting your traffic, and it's also a great idea if you're traveling and find yourself connected to a Wi-Fi network, and you want to add an extra layer of privacy for your devices and logins.

With a VPN, you're able to virtually change your location on your phone, tablet or laptop to get access to the game. Most VPNs, like our Editors' Choice, ExpressVPN, make it really easy to do this.

Using a VPN to watch or stream sports is legal in any country where VPNs are legal, including the US, UK and Canada, as long as you have a legitimate subscription to the service you're streaming. You should be sure your VPN is set up correctly to prevent leaks: Even where VPNs are legal, the streaming service may terminate the account of anyone it deems to be circumventing correctly applied blackout restrictions.

Looking for other options? Be sure to check out some of the other great VPN deals taking place right now.

ExpressVPN is our current best VPN pick for people who want a reliable and safe VPN, and it works on a variety of devices. It's normally $13 a month, and you can sign up for ExpressVPN and save 35% -- the equivalent of $8.32 a month -- if you get an annual subscription. 

Note that ExpressVPN offers a 30-day money-back guarantee.

How to watch Fury vs. Usyk in the US

Saturday's big fight is available to stream in the US via ESPN Plus for a pay-per-view price of $70. US viewers also have the option of watching the fight via dedicated DAZN for the same price, which also includes a free one-month subscription to the service as well as PPV.com, again for the same $70 PPV fee. 

ESPN's standalone streaming service costs $11 a month or $110 for an annual subscription. To watch this fight on the service you'll also need to pay a $70 PPV fee. Read our ESPN Plus review.

Saturday's fight is available to watch in the US on DAZN for $70, with that PPV fee also giving you a free one-month subscription to the service.

As well as dedicated apps for iOS and Android, there's a wide range of support for set-top boxes and smart TVs.

How to watch Fury vs. Usyk in the UK

If you live in the UK, there are three different options for watching this much anticipated fight, with DAZN, Sky Sports Box Office and TNT Sports Box Office all offering full coverage, with all three options being offered at the same PPV price of £25.

You can buy the Fury vs. Usyk fight for £25 via Sky Sports Box Office. 

You'll be able to tune in via Sky Q, Sky Plus, the Sky Sports Box Office app and website, as well as Virgin TV and BT TV.

Coverage will feature commentary from Matt Macklin and Johnny Nelson and is set to begin at 4 p.m. BST.

Live coverage of Fury vs. Usyk starts on TNT Sports PPV at 3 p.m. BST.

You'll be able to tune in via BT TV, Sky or Virgin, as well as the TNT Sports Box Office app on iOS and Android, or via Chromecast and AirPlay.

Pay the £25 PPV to watch Saturday's fight on DAZN and you'll get a free one-month subscription to the sport streaming service.

If you're an existing DAZN UK customer you'll get a small discount to the PPV price at £24.

As well as dedicated apps for iOS and Android, there's a wide range of support for set-top boxes and smart TVs. It's also worth pointing out that if you're a Sky TV customer, you can watch the action on DAZN 1 HD on channel 429.

How to watch Tyson Fury vs. Oleksandr Usyk in Canada

For Canadian fight fans, Saturday's big title fight is available to watch via streaming service DAZN. 

Pay the CA$70 PPV to watch Saturday's fight on DAZN and you'll get a free one-month subscription to the sport streaming service.

As well as dedicated apps for iOS and Android, there's a wide range of support for set-top boxes and smart TVs. 

How to watch Fury vs. Usyk in Australia 

Australian boxing fans can stream this clash via streaming service DAZN.

Pay the AU$35 PPV fee to watch Saturday's fight on DAZN and you'll get a free one-month subscription to the sport streaming service.

As well as dedicated apps for iOS and Android, there's a wide range of support for set-top boxes and smart TVs. 

Tyson Fury vs. Oleksandr Usyk full fight card

In addition to the main event, there are a number of other fights taking place in Arizona tonight.

• Tyson Fury vs. Oleksandr Usyk: Undisputed WBC, WBA, WBO and IBF heavyweight titles
  
• Jai Opetaia vs. Mairis Briedis: Vacant IBF cruiserweight title
  
• Joe Cordina vs. Anthony Cacace: IBF super-featherweight title
  
• Agit Kabayel vs. Frank Sanchez
  
• Sergey Kovalev vs. Robin Sirwan Safar
  
• Mark Chamberlain vs. Joshua Oluwaseun Wahab
  
• Moses Itauma vs. Ilja Mezencev
  
• David Nyika vs. Michael Seitz
  
• Isaac Lowe vs. Hasibullah Ahmadi