Former Wales and British and Irish Lions wing Shane Williams believes Warren Gatland's 2021 tourists will defeat world champions South Africa.

"I think the Lions have a strong enough squad to beat South Africa," said Williams.

"They have players with confidence and I think the boys will do the business."

The Lions will get together for training in Jersey before an opening match against Japan at Murrayfield on 26 June. The 37-man party will then fly out for eight games in South Africa, including the Test series which starts on 24 July and finishes on 7 August.

"They are two very strong squads," added Williams.

"South Africa are the world champions and have some the best players on the planet on that team and it's all about the match-ups as well.

"It is probably the strongest Lions squad in my lifetime. You have championship winners and players doing well for club and country with some real experience blended with young talent.

"The match-ups are fantastic, but I do think the Lions have them individually. Only time will tell and the Lions players have to play midweek games and prove to Gatland they are up for the job."

Williams also believes past history will help motivate Gatland after the 2-1 series defeat on the 2009 tour 12 years ago when the New Zealander was the forwards coach.

"I was on the 2009 tour and it was the one that got away," said Williams.

"It might have been 12 years ago, but it will be the same for Gats and he will be determined to go there and do the business."

Williams believes the ability to cope with being in a bubble for almost two months will be crucial.

"I have been in situations where you have to stay in hotels for a long time and that's difficult enough, so I feel for the lads," said Williams.

"They are probably used to it by now because they have been involved in a season in that environment.

"The Lions tour was all about the fans and the camaraderie between players and supporters and they are not going to get that experience.

"These boys know they have a job to do and the whole purpose is to win those three Tests.

"It is one of the toughest places to play rugby against the world champions. They will be focused and ready."