Saracens have named a strong starting XV to face Worcester for Saturday's Premiership London Double Header at Twickenham.
Ernst Joubert will bring down the curtain on a superb career with Saracens, with the 35-year old named at number eight for his final game before retiring.
Joubert will be joined by Kelly Brown and Will Fraser in the back-row.
At lock, Alistair Hargreaves will captain the side and he will be joined by George Kruis. Up front, Rhys Gill starts at loosehead prop and he will line-up alongside Schalk Brits and Juan Figallo.
In the halves, Ben Spencer comes into the side for Richard Wigglesworth and will partner fly-half Charlie Hodgson.
Brad Barritt continues at centre, and will be partnered by Argentine Marcelo Bosch in the Sarries midfield.
In the back three, Ben Ransom rotates with Alex Goode and will join Chris Ashton and Chris Wyles.
On the bench, Jared Saunders, Richard Barrington and Titi Lamositele are named as front-row replacements. With Jim Hamilton still sidelined with a knock, Maro Itoje is included in the 23-man squad with new-signing Samu Vunisa set to make his Saracens debut from the bench.
The evergreen Neil de Kock and in-form Owen Farrell are Sarries half-back replacements, with Nick Tompkins also included.
Speaking ahead of the game, Director of Rugby Mark McCall said: "We've had some great encounters in the Double Header fixture over the years. Worcester Warriors have made a very good start to the Premiership season, and have picked up some impressive results against Northampton Saints and Newcastle Falcons.
"They also ran a very good Gloucester team extremely close as well, so we know that we are facing a very strong Warriors outfit this Saturday.”
On Joubert's final game for the club, McCall added: "Ernst has been a truly fantastic player during his six years at Saracens.
"He has played a huge role in helping us become a side that is challenging on the field and has been extremely important in establishing a brilliant culture off the field.
"What has been so impressive has appetite to continue to learn as a player, even in the autumn years of his career.
"He was a player who set the standards both on and off the pitch, and acted as brilliant mentor and role model for the young crop of forwards.
"He has had a willingness to front up day in day out and he hardly missed a training session in six years. Ernst has been the ultimate team man, and I'm sure all Saracens fans will give Ernie the send-off he so richly deserves this Saturday.”
Meanwhile, Worcester boss Dean Ryan has made four changes to the side that defeated Newcastle Falcons three weeks ago with skipper GJ van Velze and flanker Sam Betty returning to the back-row alongside Phil Dowson.
South African international Wynand Olivier also comes back into the side in place of Alex Grove despite the centre's two-try heroics against the Falcons.
Prop Na'ama Leleimalefaga also steps into the front-row to partner Niall Annett and Nick Schonert while Donncha O'Callaghan and Darren Barry keep their starting berths in the second-row.
A formidable back three of Chris Pennell, Bryce Heem and Cooper Vuna give Warriors plenty of pace in attack, with Ryan Mills in midfield and Tom Heathcote at fly-half.
Meanwhile scrum-half Jonny Arr will make his 173rd appearance for the Warriors when he steps out on the hallowed Twickenham turf.
Director of Rugby Ryan said: "It's a great opportunity to benchmark ourselves against one of the best sides over the last three or four years.
"We've got a better idea of where we're competitive after four games and now we will be scrutinised against one of the most efficient and brutal sides in the league but we're keen to show what we can do.
"We've got a reasonable amount of experience of players who've played at Twickenham and we'll be telling everyone to go out and play the role they play every week.
"It's a great occasion for the city and the team so let's go and enjoy it.”
Form: Saracens have won their last nine matches in all tournaments since losing to Exeter Chiefs at Allianz Park in Aviva Premiership Rugby last May. Saracens only defeat in their last five visits to Twickenham came after extra time against Northampton in the Premiership Rugby final 2014. Worcester Warriors have a won 2, lost 2 record in Aviva Premiership Rugby this season, with both the victories being at Sixways and both defeats on the road. Worcester have never played a game of XVs at Twickenham before, but did appear in the Middlesex Sevens on seven occasions in the noughties. Saracens have won their last three Premiership Rugby fixtures against Warriors since Worcester’s 12-3 victory at Sixways in November 2012.
Saracens: 15 Ben Ransom, 14 Chris Ashton, 13 Marcelo Bosch, 12 Brad Barritt, 11 Chris Wyles, 10 Charlie Hodgson, 9 Ben Spencer, 8 Ernst Joubert, 7 Will Fraser, 6 Kelly Brown, 5 Alistair Hargreaves (c), 4 George Kruis, 3 Juan Figallo, 2 Schalk Brits, 1 Rhys Gill.
Replacements: 16 Jared Saunders, 17 Richard Barrington, 18 Titi Lamositele, 19 Maro Itoje, 20 Samulea Vunisa, 21 Neil De Kock, 22 Owen Farrell, 23 Nick Tompkins.
Worcester Warriors: 15 Chris Pennell, 14 Bryce Heem, 13 Wynand Olivier, 12 Ryan Mills, 11 Cooper Vuna, 10 Tom Heathcote, 9 Jonny Arr, 8 GJ van Velze (c), 7 Sam Betty, 6 Phil Dowson, 5 Darren Barry, 4 Donncha O'Callaghan, 3 Nick Schonert, 2 Niall Annett, 1 Na'ama Leleimalefaga.
Replacements: 16 Jaba Bregvadze, 17 Val Rapava Ruskin, 18 Joe Rees, 19 Tevita Cavubati, 20 Matt Cox, 21 Charlie Mulchrone, 22 Ryan Lamb, 23 Ben Howard.
Date: Saturday 28 November
Venue: Twickenham Stadium
Kick-off: 15:15 GMT
Referee: Ian Tempest
Assistant referees: Peter Huckle, Nigel Carrick
TMO: Rowan Kitt