George Lowe scored one try and saved two others as Harlequins produced an heroic defensive performance to beat Saracens 24-19 in front of a world-record crowd and extend their lead at the top of the Aviva Premiership.
Lowe is on Stuart Lancaster's list of potential England stars of the 2015 Rugby World Cup and the 22-year-old Harlequins centre proved why on the biggest stage club rugby has ever seen, with a crowd at Wembley of 83,761.
After Jordan Turner-Hall's try had put Harlequins ahead, Lowe produced a top class finish to score his side's second of the afternoon and Danny Care added their third after the break.
Saracens then threw the kitchen sink at Harlequins but Lowe kept the Premiership champions out with brilliant try-saving tackles on Michael Tagicakibau and Chris Wyles in the space of three minutes.
Harlequins were under siege and had three men sin-binned - Joe Marler, Care and Nick Easter - as they weathered wave after wave of Saracens attacks.
Richard Wigglesworth finally stole over when Marler and Care were both off the field and Owen Farrell added the conversion to his four first-half penalties.
Exeter Chiefs continued to push hard for a semi-final spot as they secured an 18-11 win over London Irish - their first victory in any competition over the Exiles.
Gonzalo Camacho and James Hanks claimed the Chiefs' tries and Ignacio Mieres kicked two penalties and a conversion.
Bath's hopes of snatching a Heineken Cup spot next season are fading fast after Northampton shrugged off the midweek suspensions of skipper Dylan Hartley and Calum Clark to claim a comfortable 26-6 win at the Recreation Ground.
Saints duly moved back into the play-off places thanks to a first-half penalty try converted by Ryan Lamb, who added two penalties and a drop goal before the break. Stephen Myler converted a catch-and-drive try credited to former Bath hooker Andy Long to seal the victory.