Irish and Quins have clashed three times this season with the away side triumphant in each instance, whilst the Exiles have won on three of their last four visits to Twickenham Stoop in the Premiership.
The two teams have met once before in a semi-final: in the 2002 Powergen Cup where London Irish won 32-27. Harlequins are playing in their first ever Premiership semi-final and have won four of their last five games in the Guinness Premiership.
London Irish were in fact the last side to defeat Quins at the Twickenham Stoop in the Premiership – 28-27 on 27 September. Only Leicester have ever won a Premiership semi-final away from home – doing so last season against Gloucester, and they had also defeated Gloucester at Kingsholm in the regular season.
London Irish are making their second appearance in the semi-finals after defeat at this stage to Leicester in 2006. The Exiles have won four of their last five games in the Guinness Premiership and were victorious their most recent away fixture 32-15 at Worcester in round 22. Irish have won just one of their last six semi-final encounters: 27-22 at Newcastle in the European Challenge Cup in April 2006.
Referee: Chris White (160th Premiership game). Assistant Referees: Roy Maybank & Paul Dix. TMO: Graham Hughes.