The Briton was stunned in June by Ruiz, an 11-1 underdog who achieved one of the biggest upsets in boxing history by dropping Joshua for a fourth and final time in the seventh round.
They fight in Riyadh, Saudi Arabia this evening on a fight card that also features the likes of heavyweight rivals Dillian Whyte, Alexander Povetkin and Filip Hrgovic. Follow all of the latest coverage below:
Ruiz vs Joshua fight preview:
What time are the ring walks?
The ring walks are set for 9.45am in Sydney, Australia (Australian Eastern Daylight Time) on Sunday morning with the fight set to begin at around 10am.
Is there a live stream?
Yes, you can watch a live stream through the Sky Sports Box Office app and website on mobile devices by ordering here.
The NOW TV Smart Stick or your NOW TV box will also allow fans to order the fight.
While US fans can stream the fight through DAZN on various platforms, including Chromecast, iOS, Android, Playstation 4 and Xbox One. A one month subscription will cost $19.99, while a year is available for $99.99.
How else can I follow the fight?
If you’re unable to get in front of a TV, you can follow the fight with live updates in the Indy Sport live blog.
The Main Event and Undercard
- Andy Ruiz vs Anthony Joshua (WBA, IBF, WBO heavyweight world title)
- Alexander Povetkin vs Michael Hunter (heavyweight)
- Dillian Whyte vs Mariusz Wach (WBC interim heavyweight title)
- Filip Hrgovic vs Eric Molina (WBC international heavyweight title)
- Mahammadrasul Majidov vs Tom Little
Joshua 2/5 (KO: 4/5, Points: 4/1)
Ruiz 2/1 (KO: 5/2, Points: 14/1)