Injuries to key players have been one of the constant themes of this year's Rugby World Cup and they remained a talking point in the run-up to the weekend's semi-finals. It was Wales's turn to suffer on Wednesday with Rhys Priestland, one of the stars of an emerging team that has shone on the World Cup stage, trying to overcome a shoulder injury in time for Saturday's last four clash with France. Fly-half Priestland, 24, who has played five of his nine career Tests at the World Cup, has won praise for the composed way he has guided the fortunes of a talented back division. The good news for Wales boss Warren Gatland -- one of three New Zealanders in charge of the remaining four teams -- is that Wales do have tried and tested alternative No 10s in veteran Stephen Jones and utility back James Hook. Hook, Wales's full-back in their opening two pool games before a shoulder problem interrupted his World Cup, confirmed his availability Wednesday. "I would be there if needed and selected," said Hook. Gatland is due to name his semi-final side on Thursday. For many of the French players involved this weekend, erasing the memory of their semi-final loss to England four years ago is a powerful motivation. France went some way to doing that with a 19-12 quarter-final victory over the English last week. But in 2007 they produced another impressive last eight performance to beat New Zealand only to fall at the next hurdle and several members of the current squad are determined not to repeat that experience. "We spoke about it as soon as the whistle went," France captain Thierry Dusautoir said of the team's achievement of reaching the final four. "There are many of us in the squad who went through 2007, we know very well what can happen after an excess of euphoria." Hooker Dimitri Szarzewski added: "We all had enormous regrets after that 2007 match against England. We couldn't wait for the next World Cup. "We have some problems but we must not let this chance to get into the final escape us." Australia continued to sweat on the fitness of star full-back Kurtley Beale ahead of their semi-final showdown against New Zealand here Sunday. Beale, rated "touch and go" for this weekend's clash, missed training on Wednesday but Wallaby captain James Horwill said: "We're still optimistic, he's working hard on his rehab and trying to do everything he can, but that's up to the medical staff and selectors to make that decision when the time comes to select the team. "He wasn't there today so we had to train with someone else in his spot, so we'll work on that." There was a time when the traffic between rugby union and rugby league was all one way. But the advent of professionalism in the 15-man game has changed the terms of trade, with several high-profile cross-code switches from league to union. Among the notable "converts" has been New Zealand's Sonny Bill Williams. The injury-hit All Blacks, who have seen fly-halves Dan Carter and Colin Slade both ruled out of the tournament with groin problems, ultimately overwhelmed Argentina 33-10 for the most convincing, in scoreline terms, of all quarter-final wins at this World Cup. But Williams, who spent five years in Australia playing rugby league for the Canterbury Bulldogs, including winning the NRL grand final in 2004 at the age of 18, said: "We haven't played our best footy yet." He added it was the chance to play in the World Cup, an event New Zealand have not won since staging the inaugural 1987 edition, that had been a major factor in his move to union. "There is nothing better than this stage," he said. "It's pretty much the whole reason why I came back here, to test myself against the best players, to try and make this team, this squad."