WATCH: Joshua weighs in three stone lighter than Ruiz Jr

Andy Ruiz v Anthony Joshua Venue: Diriyah Arena, Saudi Arabia Date: Saturday, 7 December Coverage: Live BBC Radio 5 Live commentary with live text commentary on the BBC Sport website and app 'One Night: Joshua vs Ruiz' - watch documentary which relives one of boxing's greatest upsets on iPlayer here

"He's humbled now. It will either make him a better individual, a better fighter, a better person, or it might just destroy him."

Former world heavyweight champion Mike Tyson is in no doubt about how big Saturday night is for Anthony Joshua.

Six months after the Briton was stunned by Andy Ruiz Jr in New York, he gets his shot at redemption - his chance to join greats such as Muhammad Ali, Lennox Lewis and Evander Holyfield on the list of heavyweights to reclaim world titles.

Ruiz, meanwhile, can prove one of the greatest sporting upsets in recent memory was no fluke.

Saudi Arabia is the venue for what has been billed as the 'Clash on the Dunes'.

But who will win? Here's all you need to make your mind up before the ring walks on Saturday at 20:45 GMT.

The 'what if' questions

"It has been 30 years I have been on the road for the BBC and this fight is going to be in the top six of all the events I have covered," said 5 Live Boxing's Mike Costello.

Here are some of the key questions from the original fight that have fans, pundits and the media guessing what might happen next:

Can Joshua simply fix the 'complacency' he was accused of in some quarters and be more disciplined and patient?

Or was there really something wrong behind the scenes before the first fight? (And will we find out more post-fight, as Joshua has promised?)

Will Ruiz's focus and desire have been lessened by his first victory?

And will the fact Ruiz fought six weeks before the first bout mean he is not as fit this time?

Has Joshua recovered psychologically from being knocked down four times in the first bout?

What the experts think

Joshua starts a 4-9 favourite with most bookmakers, while Ruiz is around a 2-1 underdog. You can send your own predictions for a fight that has split opinions to #bbcboxing.

BBC Sport boxing correspondent Mike Costello: "There has to be a fear that Joshua's punch resistance will not improve at this stage of his career but I believe this time he will be more patient when he has success and his power from long range will be decisive."

BBC Radio 5 Live boxing analyst Steve Bunce: "I think Ruiz might need to be rescued. I think if Joshua has his confidence back we may see Joshua win and Ruiz rescued from his bravery late in the fight."

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WBA world super-middleweight champion Callum Smith: "If Ruiz wins again I wouldn't be one bit surprised. I do think you'll see a more switched-on Joshua who is more like Lennox Lewis and Wladimir Klitschko. It could be boring but I'm going Joshua late."

Hall of fame promoter Bob Arum: "I like Ruiz to win again. He is really an under-rated guy. His low centre of gravity works well against a big heavyweight and his hand speed is phenomenal. His style plays to Joshua's weaknesses."

Former world heavyweight champion Hasim Rahman: "I am leaning at the moment to Ruiz by knockout. I just think Joshua has lost weight. I feel he may have lost muscle and that can be detrimental."

WBA and IBF world super-lightweight champion Josh Taylor: "I see Ruiz edging the fight just because of Joshua's past record in struggling against shorter, more compact opponents."

What about Joshua's weight loss?

Six months have passed since Ruiz's rotund body shape was questioned before he shocked the world. And on Friday he weighed in 15lbs heavier than last time at 20st 3lbs. He has not been heavier for a fight in more than 10 years.

Joshua's revelation earlier in fight week that he might drop from 17st 9lbs to under 17st was described as "nothing short of startling" by Costello, who added: "It makes you think, what is in his mind?"

On Friday, Joshua confirmed his prediction by weighing in at 16st 13lb - his lowest mark in five years. But what could that mean on fight night?

Added speed for Joshua? A chance to carry less bulk and aid his engine? The ability to throw snappy punches over slower, more loaded shots?

But, on the flip side, will the power that floored Ruiz in round three of their first contest be diminished? And will carrying less weight lower his resistance to punches?

And for a heavier Ruiz, is that a lack of training? Or will it make him more durable than last time, when he took some punishment and still won through?

Will it be rowdy in Saudi?

'I've had to reinvent myself' - Joshua on Ruiz Jr rematch

Very few British fans have been seen in the Saudi capital in fight week, although Friday's weigh-in saw around 200 turn out. Ruiz was also roared on by small clusters of Mexicans.

Some Joshua fans, draped in Union Jacks, told BBC Sport the access to tickets - which range from £105 to £10,500 in price - was straightforward.

Fans who do get to Diriyah Arena - and organisers say tickets were bought in 65 countries - will sit in a 15,000-seat venue that did not exist two months ago.

Neil Leifer - the photographer who captured one of the most iconic images in sport as Muhammad Ali stood over a floored Sonny Liston in 1965 - will be one of those attending. His presence alone tells you this fight is a big deal.

What next? The scenarios

A second Ruiz win would spark immediate talk of him facing WBC champion Deontay Wilder, who is due to meet Tyson Fury for a second time in February.

Wilder and Ruiz share the same advisor, so boxing could, in theory, be within touching distance of a first ever bout for all four heavyweight belts.

There is no rematch option in the contract this time, so were Joshua to win, he too could look to Fury or Wilder to set up a captivating 2020 in the glamour division.

On the other hand, a second loss would limit Joshua's options in the short term and undoubtedly produce calls for him to hang up his gloves.

Even in defeat, that would seem a harsh verdict on a man who has achieved so much in so little time.

But Costello concludes: "It will be a long, long way back."

Tyson will be ringside. So will Joshua be better or destroyed?