WALES will hold a shootout for the final spot in their back three for Twickenham when they start their World Cup campaign against Pool A whipping boys Uruguay.

Warren Gatland's men face the South American minnows at the Millennium Stadium a week on Sunday and it will be a mix-and-match team given that sterner tests lie ahead against England, Fiji and Australia.

Leigh Halfpenny's injury heartbreak has opened up a spot in the back three alongside wing George North and full-back Liam Williams for the big encounters.

Lions wing Alex Cuthbert is in pole position but has been struggling for form on the Test scene and is under pressure from Newport Gwent Dragons speedster Hallam Amos, Eli Walker and Matthew Morgan.

And backs coach Rob Howley says that the tournament opener against Uruguay will go a long way towards deciding who gets the nod for the England game on Saturday, September 26.

"Eli has come in and there is Hallam and Alex," said Howley. "Two players could be playing against Uruguay and would be up for that spot against England.

"It's important that we go into that England game with a feel-good factor and players on form.

Williams and tighthead Samson Lee are back in full training after foot and Achilles injuries respectively and are likely to both start against Uruguay.

Mike Phillips could also be in the selection mix after receiving a late reprieve following Rhys Webb's injury against Italy.

The33-year-old was axed from the training squad last month but Howley has praised the reaction of the 94-times capped veteran.

"The way he dealt with not being selected, first and foremost, was a huge plus and a positive for us," said the backs coach.

"Mike accepted that decision and wanted the best for Rhys, Lloyd Williams and Gareth Davies. He has that experience, he is a street fighter, and the physical attributes of his game are there for everyone to see.

"I think we are fortunate from a national perspective to call on someone of Mike's ability and physicality. Hopefully, over the next couple of weeks, you will be able to see some of the stronger points of his game."

With Halfpenny absent from World Cup duty - he has amassed 508 points in 62 Wales Tests - principal goalkicking duties will now pass to fly-half Dan Biggar, and Howley has no doubt about Biggar's ability to step up in Test rugby's pressure-cooker environment.

"Dan has taken over the duties several times from Leigh in the past, notably in the Wales-England game in 2013, and he kicked last Saturday as well," Howley added. "He is a quality kicker.

"The challenge for Dan - and he's matched this challenge in the regional game - is to kick and play, to be a kicker and a playmaker at international level. I have no doubt he has the qualities.

"There may be a 10-metre difference (in goalkicking range between Halfpenny and Biggar) which changes the landscape a bit, because instead of kicking for goal, we will be kicking for the corner.

"In terms of scoring tries, that will give us the ability to increase the pressure in the opposition 22."

"It is probably the case that with Leigh and his kicking prowess we haven't gone into those zones too often because we've been going for goal and building a lead from 50 to 55 metres, as you do in the international game.

"His kicking is phenomenal - I don't need to say that. He will definitely be missed."