Saracens struggled to overcome desperate Ulster defence to win their European Cup quarter-final 17-15.
The Irish team put up a magnificent fight after losing their fullback Jared Payne to a red card four minutes into the game after a mid-air clash with Saracens' Alex Goode.
Despite this, Bok scrumhalf Ruan Pienaar kicked three penalties out of five to counter Chris Ashton's try and take Ulster into the break at 9-5.
But he was still struggling with the shoulder injury which kept him on the sidelines for the past two weeks and departed shortly after the restart. Finally, England's South African lock Mouritz Botha broke through far out and Ashton scored a second try to give Saracens' a 17-9 lead. Two Paddy Jackson penalties ensured the match ended on a knife-edge.
Saracens will play Clermont in the first semi-final on 26 April.
Former Blue Bulls back row CJ Stander produced a Man of the Match performance to lead Munster to a 47-23 win over Toulouse.
He stepped on to the field as flank in the 28th minute after an injury to Munster captain Peter Mahoney and immediately took command.
The French giants were swept away by the relentless red tide early on, Keith Earls' fifth-minute try helping Munster establish a 13-9 advantage at half-time. Then two tries in five minutes, from Dave Kilcoyne and Stander, effectively ended the resistance.
Although second-half tries from Hosea Gear and Joe Tekori reduced the arrears to 27-16, Rob Penney's men made certain of their progress as Simon Zebo and Paul O'Connell added to the scoreline. Munster will meet the winner of Sunday's Toulon-Leinster clash.
Morgan Parra kicked five penalties and converted Wesley Fofana's 21st minute try to help Clermont to a 22-16 win over Leicester. The English team had clawed themselves back into contention at 19-16 when Thomas Waldrom was yellow-carded three minutes after coming on as a sub in the 61st minute.
Munster 47 Toulouse 23
Clermont Auvergne 22 Leicester 16
Ulster 15 Saracens 17
Toulon vs Leinster
Photo: Clive Rose/Getty Images