Wales squad were without the two back-rowers on a recent trip to the Olympic facility in Poland, but coach Warren Gatland has revealed that the team to play at Twickenham next weekend will be selected from the 39-man squad.
"We have established a nucleus of players who will form our RWC squad based on their performances in training over recent weeks, but it is now time to translate those efforts onto the field,” BBC Sport quotes Gatland as saying.
"The players have worked hard, but places in that final World Cup squad are still very much up for grabs and a lot will depend on what we see over the course of these next three games."
Wales will finish their preparations with a warm-up fixture against Argentina in Cardiff on August 20.
"We have not shied away from facing the top quality opposition in preparation for this World Cup and it doesn't come much tougher than facing the 2003 World Cup winners and 2007 finalists on their home patch," Gatland added.
"The warm-up fixtures will be tough, but we are in a really tough group at the World Cup and replicating those conditions can, ultimately, only be of benefit to us."
The Welsh team will commence their World Cup campaign against South Africa on September 11.