WALES head coach Warren Gatland has challenged his young guns to rise to the occasion after making six changes for tomorrow’s final Six Nations clash of the year against Scotland.

Rookie tighthead prop Rhodri Jones, 22, and winner of nine caps, has come in for three-times Grand Slam winner Adam Jones, 33, a veteran of 93 Tests, who is demoted to the replacements’ bench after last week’s disappointing 29-18 defeat to England.

And his Scarlets teammate Liam Williams, also 22, with 11 caps to his name, is given the nod at full-back in place of Leigh Halfpenny, out for the rest of the season after he dislocated his shoulder at Twickenham on Sunday making a try-saving tackle.

Dan Biggar, who helped steer Wales to retaining their Six Nations title in 2013, gets his first start of this campaign, replacing the often egregious Rhys Priestland at outside-half, the Scarlets man still being included on the bench for the Millennium Stadium clash after his shocking form.

Mike Phillips gets his place back at scrum-half after being dropped as first choice No 9 for the victory over France (27-6) and England after Rhys Webb injured his ankle in the setback in west London, Rhodri Williams set to win his third cap tomorrow as back up.

Former Newport Gwent Dragons hero Luke Charteris is also back after missing last week’s loss with a neck injury, the Perpignan second row coming in for Parc y Scarlets man Jake Ball who drops down among the substitutes.

Another Scarlets man to get a chance to shine is Ken Owens, preferred at hooker instead of 2013 British and Irish Lions series winner Richard Hibbard who is on the bench, the man nicknamed ‘Cannonball Ken’ by teammates making his first Six Nations start since Wales won the Triple Crown by beating England 19-12 at Twickenham in February 2012.

Despite being yellow carded in successive tournament games against France and England, loosehead Gethin Jenkins keeps his place and will become his country's most-capped player.

The Cardiff Blues and Lions prop will make his 105th appearance tomorrow, moving one ahead of fly-half Stephen Jones.

On the changes, Gatland said: “Some players have been training well and making an impact off bench.

“For some, it’s a reward and the fact is we have freshened it up and changed it a little bit and some other changes have been forced upon us.

“The impact of Ken Owens and Rhodri Jones off the bench was evident. We’ve got to keep developing depth in the front row and give people a chance.

“Confident youngsters will take chance with both hands.”

About recalling Biggar and dropping Priestland, Gatland added: “Dan’s been unlucky. We’ve given Rhys an opportunity there (No 10).

“You want to give player a run of games, but this is a chance to bring Dan back into fold to hopefully make an impact.”

Wales: Liam Williams (Scarlets); Alex Cuthbert (Cardiff Blues), Jonathan Davies (Scarlets), Jamie Roberts (Racing Metro), George North (Northampton Saints); Dan Biggar (Ospreys), Mike Phillips (Racing Metro); Gethin Jenkins (Cardiff Blues), Ken Owens (Scarlets), Rhodri Jones (Scarlets), Luke Charteris (Perpignan), Alun Wyn Jones (Ospreys), Dan Lydiate (Racing Metro), Sam Warburton (Cardiff Blues, capt), Taulupe Faletau (Newport Gwent Dragons).

Replacements: Richard Hibbard (Ospreys), Paul James (Bath Rugby), Adam Jones (Ospreys), Jake Ball (Scarlets), Justin Tipuric (Ospreys), Rhodri Williams (Scarlets), Rhys Priestland (Scarlets), James Hook (Perpignan).