Chris Jack, the All Blacks lock, returns to the scene of his World Cup nightmare on Saturday, hoping to lead Saracens to victory over the Ospreys in the EDF Energy Cup semi-final in Cardiff.

The last time he played at the Millennium Stadium, Jack was on the receiving end of a 2007 World Cup quarter-final defeat by France and subsequently quit Test rugby.

But he is now hoping to enjoy success with Saracens, who have also reached the quarter-finals of the Heineken Cup - again against Ospreys - and are pushing for a top-four finish in the Guinness Premiership.

Jack said: "My last visit to the Millennium Stadium wasn't great and I definitely haven't erased what happened against France from my memory.

"I'm sure that game will coming flooding back when I get into the dressing room on Saturday, but I am there to play for Saracens this time."

The New Zealander recognises this is not the best time to be taking on the Ospreys at the home of Welsh rugby, just one week after the nation celebrated another Grand Slam triumph.

"A lot of the Ospreys guys played in the Wales' Grand Slam side and that makes it really exciting for us because none of the Sarries made the England team for the Six Nations," Jack said. "It's an awesome challenge for us to play, basically, the Wales team.

"Our last four or five performances have not been as good as our form around Christmas and if we come away from this season with nothing then all the good work at the start of the season will have been lost."

Jack is at pains not to stir up controversy over the decision to drop Saracens centre Andy Farrell from the England squad but added: "There is definitely a team that could play fantastic rugby for England. When they are selected they will be a great team.

"It's not just Faz, there are a number of guys who are playing exceptional rugby and could be chosen. What surprised me when I got here is that I discovered teams play open and wide rugby, but when they turn out for England they don't."

Alan Gaffney, the Sarries director of rugby, is concerned about the recent slump in form, but still believes his men retain enough momentum to cause an upset in Cardiff.

He said: "We have painted ourselves into this position and have to step things up and finish the last lap strongly.

"This semi-final is a huge ask for us but I believe opponents didn't attack Wales during the Six Nations with the ball in hand.

"This is what we are going to have to do against the Ospreys and I believe we can be successful by adopting that kind of positive attitude."

Meanwhile, Ireland will begin their search for a new coach today following Eddie O'Sullivan's resignation late last night.

Munster coach Declan Kidney is favourite to succeed O'Sullivan, with South Africa's World Cup-winning coach Jake White another strong candidate.

Ireland's fourth-place finish in the Six Nations was their worst since 1999. But O'Sullivan, 49, did preside over three Triple Crown successes and had more than three years remaining on his contract.

• Tickets are available for the EDF Energy Cup Final at Twickenham on 12 April. Visit edfenergyrugby.com or call 0870 902 0000 for more information.