Ruddock goes into the match without first-choice midfield pairing Gavin Henson (groin) and Tom Shanklin (knee), while leading contender Sonny Parker is battling a hamstring injury. The Blues' Jamie Robinson is still finding his feet after a year out with a knee injury and the Dragons' Hal Luscombe is out of the equation after breaking a thumb against Edinburgh on Friday night.
Ruddock has the choice of the Dragons' Ceri Sweeney in the No. 12 jersey, while veteran Mark Taylor may earn a recall if Parker fails next week's fitness test. Skipper Gareth Thomas played at outside centre for Toulouse on Saturday and may move from fullback to fill the problem area.
World-class prop Gethin Jenkins (shoulder) will also miss the autumn Test series, while doubts linger over Lions star Ryan Jones after he injured a shoulder against Bath a week ago. Ironically, the man in the Bath No. 8 jersey that day is being tipped as Jones's replacement in the Wales lineup.
Gareth Delve has been tipped as a Wales star for several years, but a serious shoulder injury meant his 2003 match against the Barbarians is his only match in the red jersey. But after an eye-catching performance in Bath's Powergen Cup victory over the Ospreys, his name is back in the headlines.
"I got a text from Scott Johnson after the Ospreys game, asking if Gareth was available for Wales squad training," Bath coach John Connolly said. "Gareth is a big, strong man. He's incredibly athletic, he's a massive ball-carrier, a good defender and he has the physicality for Test rugby.
"I think Gareth will be involved in the autumn. Ryan Jones is a good player, but he took another knock against us so you don't know. And Colin Charvis is competing with Gareth - I think Charvis is an openside flanker. I think you'll see Gareth in the 22 for the autumn Tests."
Connolly said the most exciting thing about Delve was that he still had a lot of improvement in him after his horror run of injuries.
"Gareth is definitely on an upward spiral - he didn't play for three years and it's always going to take a year to come back into it," the Australian said. "He came into some form slowly last year and he's really stepping up to the mark this season. Against the Ospreys, he was the best backrower, and the best thing is that you know he has a lot of improvement in him."
As the countdown continues for RWC2015, Tournament Chief Executive Debbie Jevans visited the Millennium Stadium to discuss preparations for the eight matches and reveal the positive news that 100,000 tickets for games at the home of Welsh rugby have sold in the last seven days.
Jason Harries is targeting a first win on the World Series circuit this season with Wales. The series returns to action this weekend in Dubai where Harries is part of a team hoping to build from its efforts in round one in October.
Wales skipper Jevon Groves says his side have addressed a few points from Gold Coast and aim to 'hit the ground running' in the next two rounds of the World Series, kicking off with this weekend in Dubai before heading off to South Africa next week.
Wales Sevens manager Steff Thomas is hopeful his side can build from a quarter-final spot in the opening round of the World Series in Australia when his side take part in the forthcoming double header in Dubai and South Africa.