Cardiff Blues director of rugby Phil Davies has warned his side they must fight fire with fire if they are to get the better of regional rivals Ospreys in the RaboDirect PRO12. The game may have been billed as a clash between two of the best openside flankers in the world in Blues’ Sam Warburton and Ospreys’ Justin Tipuric but Davies has warned there will be contests all over the field. Warburton is not the only member of Wales’ Six Nations-winning side to start the game with man of the tournament Leigh Halfpenny at full-back and scrum-half Lloyd Williams also starting. But after seeing his side slip to three straight defeats in the RaboDirect PRO12 since their 17-16 victory against Edinburgh at Murrayfield February 15, Davies admits each player must win their own battle to get back to winning ways. “We've got plenty to play for and playing at the Millennium Stadium just gives it that extra edge,” he said. “Coming off the back of Wales winning the Six Nations is great and hopefully it's an occasion that can showcase the regional game in Wales. “Facing the Ospreys is a challenge and we've certainly not performed to the standards we have aspired to, we have performed well, but we are coming up against arguably the best pack in the competition. “It's not going to be easy but it's a challenge we are looking forward to and we will be making it a challenge for the Ospreys as well. “We have to work well as a collective unit. There will be some outstanding players on display and there will be some intriguing battles all over the pitch. “A lot of players know each other well but at the end of the day it's about Cardiff Blues v Ospreys.” The Blues are unbeaten in their last three matches at the Millennium Stadium, which were all the in European Cup, and won 40-31 against Leinster on their only previous encounter there in the PRO12, in May 2006. The Blues’ only two wins in their last nine contests with fellow Welsh regions in the competition have both been against Newport Gwent Dragons. Ospreys' sole defeat in their last nine RaboDirect PRO12 matches since November was 10-22 to Connacht in Galway in round 15. Ospreys only two previous visits to the Millennium Stadium were both semi-final encounters in the Anglo-Welsh Cup, in 2007 and 2008, winning them both, against Cardiff Blues and Saracens respectively. Ospreys have won their last seven clashes with fellow Welsh regions in the PRO12. Cardiff Blues have not beaten Ospreys since a 27-25 victory at the City Stadium on New Year's Eve 2010 and with fly-half Dan Biggar back pulling the strings and Tipuric looking to get one over on his Wales team-mate things are unlikely to get any easier. Richard Hibbard and Adam Jones, two thirds of Wales’ front row, also start while Alun Wyn Jones captains the side with head coach Steve Tandy issuing a warning to keep their focus on securing a play-off spot. “We’ve only got four games left in the regular season so each one is crucial now and it’s vital that we are on the top of our game, on and off the field,” he said. “It’s a big occasion for regional rugby in Wales on Saturday, and it’s going to be great to play at the Millennium Stadium with a big Ospreys crowd behind us, but we mustn’t allow ourselves to be distracted. “We have to be 100 per cent focused on the job, and we have to kick on from last weekend’s win to allow us to really build some momentum going into the final three games, starting with Treviso at the Liberty in two weeks. “We are very proud of what we’ve achieved in this league, and to be the reigning champions, and we have to put in four champions performances if we are going to book a place in the play-offs.” At Millennium Stadium, 5.15pm. Live on S4C Referee: Nigel Owens (WRU, 95th competition game) Assistant Referees: Ian Davies, Wayne Davies (both WRU) Citing Commissioner: Denis Jones (WRU) TMO: Nigel Whitehouse (WRU)