Twenty-three South Africans will take part in the four matches this weekend.
Ulster were given a massive lift when their talismanic scrumhalf Ruan Pienaar was given the all-clear to play in the European Cup quarter-final against Saracens on Saturday.
The Irish side has home advantage, thanks in no small measure by the outstanding form of the Springbok No 9. Back in January, he capped his European season by scoring all of Ulster's points against Leicester with a try, conversion and five penalties as they won 22-19 away to set up the meeting with Saracens. But he had been struggling to overcome a shoulder injury and Ulster held off for as long as possible to get him on the field.
Johann Muller, coming to end of his career as captain of the Ulster team, is aware of the task ahead, having been beaten by Saracens at this stage last year in London.
'Saracens totally outplayed us last year. They're a great side and they don't mind going away from home and getting results. We haven't achieved anything yet. We finished top of our pool and top of the log but a lot of great teams in the history of this tournament have been in exactly the same situation as we're in now and they've slipped up in the quarter or semi-finals. There's a huge amount of work left for us if we want to achieve something great.'
Saracens, meanwhile, have almost a full complement of players to pick from, and are starting with Ernst Joubert (No 8) and Schalk Britz (No 2), with scrumhalf Neil de Kock taking his turn on the bench for Richard Wigglesworth. England loose forward Billy Vunipola was also deemed fit enough to resume playing after his ankle injury sustained in England colours in February.
Toulon will be without Bakkies Botha, whose broken arm is not yet strong enough for such a match against Leinster at Stade Felix Mayol. And to add to their worries, New Zealand lock Ali Williams is also out, with an injured bicep, but that has opened the way for Danie Rossouw to start. They also have Juan Smith, who is in sparkling form and growing stronger by the week, as well as Craig Burden. This could also be the week that Bryan Habana makes his return, from the bench, after the hamstring injury which has kept him on the sidelines since December.
Toulon scrumhalf Michael Claassens acknowledges the threat posed by three-time European champions Leinster.
'They've been one of the top teams in the European Cup for years so it will probably be our toughest game of the season. They've got strength all over the park in their organisation, their coaching, the players they have, with good forwards and good backs. They're a really difficult team to play against and they're Irish as well so will be very passionate.'
Toulouse feature Jano Vermaak and Gurthrö Steenkamp in the run-on team against Munster. The Irish start with BJ Botha and have CJ Stander in reserve. They are also giving former Stormer Gerhard van den Heever his first taste of European rugby on the bench.
Clermont Auvergne lost their opening pool match against Racing Métro but hit back to win all their remaining games to claim a home quarter-final against the Leicester Tigers. Nobody can ever feel certain of winning in a knockout game, but after 74 successive wins at Stade Marcel Michelin, 'Les Jaunards' will feel pretty relaxed on Saturday.
MUNSTER vs TOULOUSE
Saturday, Thomond Park, Limerick, 14:30 (SA time)
Munster – 15 Felix Jones, 14 Keith Earls, 13 Casey Laulala, 12 James Downey, 11 Simon Zebo, 10 Ian Keatley, 9 Conor Murray, 8 James Coughlan, 7 Tommy O'Donnell, 6 Peter O'Mahony (c), 5 Paul O'Connell, 4 Dave Foley, 3 BJ Botha, 2 Damien Varley, 1 Dave Kilcoyne.
Subs: 16 Duncan Casey, 17 John Ryan, 18 Alan Cotter, 19 Donncha O'Callaghan, 20 CJ Stander, 21 Duncan Williams, 22 JJ Hanrahan, 23 Gerhard van den Heever.
Toulouse – 15 Maxime Médard; 14 Yoann Huget, 13 Florian Fritz, 12 Gael Fickou, 11 Hosea Gear; 10 Lionel Beauxis, 9 Jano Vermaak, 8 Louis Picamoles, 7 Joe Tekori, 6 Yacouba Camara, 5 Patricio Albacete (c), 4 Yoann Maestri, 3 Yohan Montes, 2 Christopher Tolofua,1 Gurthro Steenkamp.
Subs: 16 Jaba Bregvadze, 17 Cyril Baille, 18 Schalk Ferreira, 19 Romain Millo-Chluski, 20 Gillian Galan, 21 Jean-Marc Doussain, 22 Luke McAlister, 23 Yannick Nyanga.
CLERMONT vs LEICESTER
Saturday, Stade Marcel-Michelin, 17:00 (SA time)
Clermont – 15 Jean-Marcellin Buttin, 14 Noa Nakaitaci, 13 Aurélien Rougerie (c), 12 Wesley Fofana, 11 Naipolioni Nalaga; 10 Brock James, 9 Morgan Parra, 8 Fritz Lee, 7 Damien Chouly, 6 Julien Bonnaire, 5 Nathan Hines, 4 Jamie Cudmore, 3 Davit Zirakashvili, 2 Benjamin Kayser, 1 Thomas Domingo.
Subs: 16 Ti'i Paulo, 17 Vincent Debaty, 18 Clément Ric, 19 Julien Pierre, 20 Alexandre Lapandry, 21 Thierry Lacrampe, 22 Mike Delany, 23 Benson Stanley.
Leicester – 15 Matthew Tait, 14 Blaine Scully, 13 Manu Tuilagi, 12 Anthony Allen, 11 Vereniki Goneva, 10 Owen Williams, 9 Ben Youngs, 8 Jordan Crane, 7 Julian Salvi, 6 Jamie Gibson, 5 Ed Slater (c), 4 Louis Deacon, 3 Logovii Mulipola, 2 Tom Youngs, 1 Marcos Ayerza.
Subs: 16 Rob Hawkins, 17 Boris Stankovich, 18 Fraser Balmain, 19 Graham Kitchener, 20 Thomas Waldrom, 21 David Mele, 22 Toby Flood, 23 Scott Hamilton
ULSTER vs SARACENS
Saturday, Ravenhill Stadium, Belfast, 19:30 (SA time)
Ulster – 15 Jared Payne, 14 Andrew Trimble, 13 Darren Cave, 12 Luke Marshall, 11 Tommy Bowe; 10 Paddy Jackson, 9 Ruan Pienaar, 8 Nick Williams, 7 Chris Henry, 6 Roger Wilson, 5 Dan Tuohy, 4 Johann Muller (c), 3 John Afoa, 2 Rory Best,1 Tom Court.
Subs: 16 Rob Herring, 17 Andrew Warwick, 18 Ricky Lutton, 19 Iain Henderson, 20 Stephen Ferris, 21 Robbie Diack, 22 Paul Marshall, 23 Craig Gilroy.
Saracens – 15 Alex Goode, 14 Chris Ashton, 13 Duncan Taylor, 12 Brad Barritt, 11 David Strettle, 10 Owen Farrell, 9 Richard Wigglesworth, 8 Ernst Joubert, 7 Jacques Burger, 6 Billy Vunipola, 5 Mouritz Botha, 4 Steve Borthwick (c), 3 James Johnston, 2 Schalk Brits,1 Mako Vunipola.
Subs: 16 Jamie George, 17 Richard Barrington, 18 Matt Stevens, 19 Eoin Sheriff, 20 Kelly Brown, 21 Neil de Kock, 22 Charlie Hodgson, 23 Chris Wyles.
TOULON vs LEINSTER
Sunday, Stade Félix-Mayol, 17:30 (SA time)
Toulon – 15 Delon Armitage, 14 Drew Mitchell, 13 Mathieu Bastareaud, 12 Matt Giteau, 11 David Smith; 10 Jonny Wilkinson (c), 9 Sebastien Tillous-Borde, 8 Steffon Armitage, 7 Juan Fernandez Lobbe, 6 Juan Smith, 5 Jocelino Suta, 4 Danie Rossouw, 3 Carl Hayman, 2 Craig Burden, 1 Xavier Chiocci.
Subs: 16 Jean-Charles Orioli, 17 Florian Fresia, 18 Martin Castrogiovanni, 19 Virgile Bruni, 20 Bryan Habana, 21 Maxime Mermoz, 22 Michael Claassens, 23 Konstantine Mikautadze.
Leinster – 15 Rob Kearney, 14 Fergus McFadden, 13 Brian O'Driscoll, 12 Gordon D'Arcy, 11 Dave Kearney, 10 Jimmy Gopperth, 9 Eoin Reddan, 8 Jamie Heaslip (c), 7 Shane Jennings, 6 Rhys Ruddock, 5 Mike McCarthy, 4 Devin Toner, 3 Mike Ross, 2 Richardt Strauss,1 Cian Healy.
Subs: 16 Sean Cronin, 17 Jack McGrath, 18 Martin Moore, 19 Leo Cullen, 20 Jordi Murphy, 21 Isaac Boss, 22 Ian Madigan, 23 Zane Kirchner.
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