The former Wales pair - who played together in two Grand Slams - will be covering the campaign as pundits for broadcasters Premier Sports.
Ahead of the league getting underway this weekend, they have been giving their thoughts on the prospects for the four regions.
Former wing legend Williams said: “I think the Ospreys will probably be the strongest Welsh team with the squad they have.
“They showed their potential last season, but didn’t quite get to where they wanted to get.
“When they beat Glasgow up at Scotstoun in March, that was pretty special and I felt right, that’s it, they had turned the corner. It was a really good performance. But then they dropped the standard again.
“So they probably under-achieved last year, overall.
“But if they can show a bit more consistency this season, I do believe they will probably end up on top compared to the other regions.
“Their pack is stronger and bigger and they have got the talent and the skill in the squad.”
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Looking at the other Welsh sides, the 87-cap Williams said: “The Scarlets were good last year, reaching the play-offs. That was a real positive push forward.
“So, they will want to keep that momentum going, while Cardiff are always there or thereabouts. They are a formidable team at home and I enjoy the style of rugby they are playing. Both of those sides can play some attractive rugby.
“We don’t talk about the Dragons that much, but they are a side that does have potential with the personnel and experience they have brought in. I think they have made some positive signings.
“Let’s be honest, they can’t be any worse than last year. But I still see them probably finishing bottom of the four regions.”
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Williams concluded: “I am relatively positive about the regions this year. We just want to see progress and for all of them to improve.
“If you look at the squads, you do feel they are capable of some big scalps as the season goes on. They can ruffle a few feathers.”
Adding his views, former centre Shanklin said: “If you look at the four regions, when they can field their strongest teams, it’s pretty good.
“I still think the Ospreys have got the biggest pack and probably the best pack. If they can stay fit, then I think they probably just slightly edge it.
“The Scarlets and Cardiff can play some brilliant rugby. We have seen that with the results they have had, while the Dragons have made quite a lot of good signings.
“If you are looking for markers, you would like to see every Welsh team do better than last year.
“So that would be the Scarlets finishing seventh, Cardiff reaching eighth, the Ospreys moving up the table and the Dragons getting more wins.
“I think that’s possible, definitely so for the Ospreys and the Dragons.
“It’s a short opening block of five games. I just hope every Welsh team can get a minimum of two wins under their belt before the block is ended.
“As for the season overall, success for me would be two Welsh teams in the top eight at the end of the year. That means play-offs, that means Champions Cup.”
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Turning to the title favourites, Shanklin predicted: “Leinster or Bulls. That probably depends on who gets the top seed and a home draw all the way through. They are the top two, with the Stormers just slightly behind. Then you’ve got Munster and Glasgow as well.”
Williams chimed in, saying: “It’s always Leinster isn’t it? It was Leinster when we were playing, for God’s sake!
“Their strength in depth and the players they seem to pull off the conveyor belt is frightening, really, and I am sure we will see a few more of those this year.
“It’s all about consistency and that winning mentality and they’ve got it.
“But these South African teams are getting better. We remember when they first came in the URC, they really struggled. Then all of a sudden…
“I can sit down and watch these South African teams twice over. I am a huge fan of the style of rugby they play.
“They are just unbelievable at times, with their steppers and the ferocity of their packs. Those are the teams that you know can beat Leinster.
“You’ve got teams from five different countries and all nations play different styles of rugby. It’s just whose tactics are best on the day and what coach has done his homework.”
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Tom Shanklin and Shane Williams are part of the Premier Sports team showing every game live from the BKT United Rugby Championship. The new URC season kicks off live on Premier Sports this weekend (September 26-28). Premier Sports will show 400+ live rugby games during the season including URC, Investec Champions Cup, EPCR Challenge Cup, Top 14, Japan Rugby League One and MLR from the USA. To join in visit www.premiersports.com
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Latest odds: (courtesy of DragonBet)
2025-26 URC Championship
Top Welsh Region (to finish highest in the table Regular Season)
7/4 - Scarlets
15/8 - Cardiff Rugby
5/2 - Ospreys
12/1 - Dragons
2025-26 URC Championship
Cardiff Rugby Specials
Champions:- 260/1
Beaten Finalists:- 130/1
To make the Play-offs (Top 8):- 10/3
Cardiff Rugby to finish above Scarlets (Regular Season):- Evens
Cardiff Rugby to finish above Ospreys (Regular Season):- 8/11
Harri Millard (Top tries scorer):- 5/1
Scarlets Specials
Champions:- 250/1
Beaten Finalists:- 125/1
To make the Play-offs (Top 8):- 3/1
Scarlets to finish above Cardiff Rugby (Regular Season):- 8/11
Scarlets to finish above Ospreys (Regular Season):- 8/13
Blair Murray (Top tries scorer):- 5/1
Ospreys Specials
Champions:- 280/1
Beaten Finalists:- 140/1
To make the Play-offs (Top 8):- 7/2
Ospreys to finish above Cardiff Rugby (Regular Season):- Evens
Ospreys to finish above Scarlets (Regular Season):- 6/5
Keelan Giles (Top tries scorer):- 5/1
Dragons Specials
Champions:- 1,000/1
Beaten Finalists:- 500/1
To make the Play-offs (Top 8):- 50/1
Dragons to finish above Cardiff Rugby (Regular Season):- 11/2
Dragons to finish above Scarlets (Regular Season):- 6/1
Dragons to finish above Ospreys (Regular Season):- 9/2
Rio Dyer (Top tries scorer):- 7/2
