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:
Joshua able to wrap his arm around Ruiz when he lunges in.
Joshua hits after the referee breaks the action. He gets a telling off too.
Big left from AJ, will he fight back or go back to boxing? Both fighters hug each other, will this finally catch fire?
Bellew has it 69-64, round 4 scored to Ruiz. Macklin has it the same too.
Ruiz frustrated in the last, clubbing to the body when the fighters held.
Can he turn the tide? Or will Joshua put his foot on the gas if the openings come?
Joshua caught as he tried to lunge in with a big right, still cagey from the outside.
Joshua opens up, lands a couple of clean rights, but that’s what Ruiz wants: openings. Not many so far.
Verbals at the end from Joshua, is he growing in confidence? Big right ends the round, too.
Joshua absorbs a clean shot from Ruiz, moves away fine though.
Gorgeous left hook from a short range.
Joshua on the back foot again and just showing Ruiz some different angles.
Will his gas tank hold? A nice jab from AJ, Ruiz caught flush but not deterred.
Both men clenching, Ruiz determined to get out and get going again.
Ruiz is getting closer, as Bellew points out. Jab lands on AJ as he ducks in and out of range.
Dangerously close there, AJ missed with a big right. Clubbing right from Ruiz, this is better from the champion. Joshua counters with a big right as the round closes inside the final 30 seconds.
Ruiz looking a bit rushed. Joshua circling.
Great start from the former champion.
Tense stuff, this, not much landed so far.
Lovely jab from Joshua, now goes down low with a left hook. Ruiz unable to close the gap so far.
Ruiz still taking the centre of the ring.
Good jab from Ruiz there, quick and hard. It snapped AJ’s head back. He’s still on the outside. This is the plan, then. Joshua now with the jab, impressive display so far. Gorgeous left hook by AJ.
Joshua is comfortable, one-two, leaned in. Joshua now cut! WOW! Clash of heads.
Beautiful right from AJ at the end of the first, he was winning anyway, but he stamped home the advantage.
Ruiz narrowly missed on the counter, though, there’s the danger.
Joshua straight out to the middle of the ring, no running just yet, jabbing high and low.
Ruiz now pushing him back, dipping low, not throwing, just having a look.
Now one shot from Ruiz down low. Joshua on the outside now, jabbing, concentrating fully, a wide left comes around the guard of Ruiz.
Big right from AJ, and Ruiz is cut! Wow! Drama!
Joshua bows as he has his name announced.
Ruiz, in gold trunks, dipping at the hips, bashes his gloves together, he loves the ovation.
First the US anthem for Ruiz…
Here comes Ruiz!
A more impressive ring walk, for what it’s worth – probably nothing.
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)