Preview: Saracens v London Welsh

Saracens boss Mark McCall has rung the changes for Saturday's Premiership clash against London Welsh at Allianz Park.

McCall has made nine changes - including two positional switches - from his run-on side that beat Sale in the European Champions Cup last weekend.

Ernst Joubert captains Sarries, with the experienced South African number eight packing down alongside Kelly Brown and Jackson Wray in the back row.

At lock, George Kruis continues in the number four jersey and is joined by Scotland international Jim Hamilton in the heart of the Saracens engine room.

In the front row, Mako Vunipola starts at loosehead prop, with James Johnston at tighthead - hooker Brett Sharman starts his first Premiership game for the club.

At scrum-half, Neil de Kock comes in for Richard Wigglesworth to partner fly-half Owen Farrell, whilst in the midfield Duncan Taylor starts at inside centre alongside Marcelo Bosch.

In the back three, Chris Wyles starts on the left wing, with Chris Ashton wearing the number 14 shirt - Ben Ransom starts at full-back.

Meanwhile, London Welsh have made 11 changes, including four positional, for this encounter.

Taione Vea, Peter Browne, James Down, Carl Kirwan, Lachlan McCaffrey, Rob Lewis, Olly Barkley and Elliot Kear all remain from the starting line up which lost out to Edinburgh at the Kassam Stadium last weekend in the European Rugby Challenge Cup.

In the backs, Will Robinson starts at full-back with Elliot Kear moving to the left wing. Seb Stegmann is named on the right wing. Olly Barkley moves from fly-half to inside centre with Nic Reynolds returning to the side at outside centre.

Rob Lewis and Piri Weepu form a new look halfback partnership.

In the forwards, Ricky Reeves and Koree Britton come in to the front row. Peter Browne moves from blindside flanker to the second row, while Lachlan McCaffrey takes over the number six jersey. Tonga international Optei Fonua starts at Number eight.

Flanker Carl Kirwan will captain the side.

Form: The Exiles' return to the top flight has been a trial by fire so far, still searching for a win in all competitions after two back-to-back European losses against Edinburgh. Allianz Park has very rarely proved a place where away teams can improve on their form, as Saracens have lost just one of their last 11 matches at home - the defeat to Saints last month. The Exiles' sole away win in Aviva Premiership Rugby came at Sale in 2012, and for Saracens full-back Ben Ransom, his side's European pick-me-up has arrived just in time for Christmas.

The teams:

Saracens: 15 Ben Ransom, 14 Chris Ashton, 13 Marcelo Bosch, 12 Duncan Taylor, 11 Chris Wyles, 10 Owen Farrell, 9 Neil De Kock, 8 Ernst Joubert (c) 7 Kelly Brown, 6 Jackson Wray, 5 Jim Hamilton, 4 George Kruis, 3 James Johnston, 2 Brett Sharman, 1 Mako Vunipola.
Replacements: 16 Jamie George, 17 Richard Barrington, 18 Petrus Du Plessis, 19 Mouritz Botha, 20 Billy Vunipola, 21 Richard Wigglesworth, 22 Charlie Hodgson, 23 Nick Tompkins.

London Welsh: 15 Will Robinson, 14 Seb Stegmann, 13 Nic Reynolds, 12 Olly Barkley, 11 Elliot Kear, 10 Piri Weepu, 9 Rob Lewis, 8 Opeti Fonua, 7 Carl Kirwan (c), 6 Lachlan McCaffrey, 5 James Down, 4 Peter Browne, 3 Taione Vea, 2 Koree Britton, 1 Rickey Reeves.
Replacements: 16 Nathan Morris, 17 Nathan Trevett, 18 Ben Cooper, 19 Dean Schofield, 20 Ben Pienaar, 21 Paul Rowley, 22 Tom May, 23 Nick Scott.

Date: Saturday, December 20
Kickoff: 15:00 GMT
Venue: Allianz Park
Referee: Ian Tempest
Assistant Referees: Roger Baileff, Simon McConnell
TMO: Keith Lewis