Judgement Day teams: Scott Williams returns for Scarlets

Over 62,000 supporters are expected for Saturday's Judgment Day double-header at the Principality Stadium as Cardiff Blues face the Ospreys and the Dragons tackle the Scarlets.

Scott Williams makes his return from injury for the Scarlets while fellow Wales international Dan Lydiate is named at No 8 for the Ospreys.

Cardiff Blues v Ospreys (2.30pm)

Cardiff are without Wales duo Lloyd Williams and Rhys Patchell after they failed to recover from the injuries suffered in their PRO12 win over the Dragons on April 17.

Matthew Rees is preferred to Kristian Dacey at hooker while Josh Turnbull moves into the second row to accommodate Josh Navidi's inclusion at No 8.

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The Ospreys have named Wales flanker Dan Lydiate at No 8 due to the injury-enforced absence of Dan Baker. Rhys Webb and Dan Biggar are named at half-back.

Cardiff are seeking a fifth successive PRO12 victory for the first time since 2010 but the Ospreys have won all five of their previous appearances at the Principality Stadium.

Cardiff Blues: 15 Dan Fish, 14 Aled Summerhill, 13 Garyn Smith, 12 Rey Lee-Lo, 11 Tom James, 10 Gareth Anscombe, 9 Lewis Jones; 1 Gethin Jenkins (c), 2 Matthew Rees, 3 Taufa'ao Filise, 4 Josh Turnbull, 5 James Down, 6 Sam Warburton, 7 Ellis Jenkins, 8 Josh Navidi.

Replacements: 16 Kristian Dacey, 17 Brad Thyer, 18 Dillon Lewis, 19 Jarrad Hoeata, 20 Manoa Vosawai, 21 Tomos Williams, 22 Jarrod Evans, 23 Gavin Evans.

Ospreys: 15 Dan Evans, 14 Hanno Dirksen, 13 Jonathan Spratt, 12 Owen Watkin, 11 Ben John, 10 Dan Biggar, 9 Rhys Webb (c); 1 Nicky Smith, 2 Scott Baldwin, 3 Dmitri Arhip, 4 Adam Beard, 5 Rynier Bernardo, 6 Olly Cracknell, 7 James King, 8 Dan Lydiate.

Replacements: 16 Sam Parry, 17 Gareth Thomas, 18 Aaron Jarvis, 19 Rory Thornton, 20 Sam Underhill, 21 Brendon Leonard, 22 Sam Davies, 23 Josh Matavesi.

Ulster v Leinster (3pm, live on Sky Sports 1 HD)

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Ulster: 15 Jared Payne, 14 Andrew Trimble, 13 Luke Marshall, 12 Stuart McCloskey, 11 Craig Gilroy, 10 Paddy Jackson, 9 Ruan Pienaar; 1 Callum Black, 2 Rory Best (c), 3 Ricky Lutton, 4 Pete Browne, 5 Franco van der Merwe, 6 Iain Henderson, 7 Chris Henry, 8 Sean Reidy.

Replacements: 16 Rob Herring, 17 Kyle McCall, 18 Andy Warwick, 19 Robbie Diack, 20 Roger Wilson, 21 Paul Marshall, 22 Stuart Olding, 23 Darren Cave.

Leinster: 15 Rob Kearney, 14 Isa Nacewa (c), 13 Garry Ringrose, 12 Ben Te'o, 11 Dave Kearney, 10 Johnny Sexton, 9 Luke McGrath; 1 Jack McGrath, 2 Richardt Strauss, 3 Tadhg Furlong, 4 Devin Toner, 5 Hayden Triggs, 6 Rhys Ruddock, 7 Josh van der Flier, 8 Jamie Heaslip.

Replacements: 16 Sean Cronin, 17 Peter Dooley, 18 Mike Ross, 19 Mick Kearney, 20 Jordi Murphy, 21 Eoin Reddan, 22 Ian Madigan, 23 Luke Fitzgerald.

Dragons v Scarlets (5pm)

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Scott Williams makes his first appearance of the season for the Scarlets after recovering from the knee ligament injury suffered during the Rugby World Cup.

Scrum-half Aled Davies replaces Gareth Davies and Michael Collins comes in at full-back as the Scarlets seek a victory that will keep their top-four hopes alive.

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Kingsley Jones makes three changes to the Dragons team that were beaten by Montpellier, with Angus O'Brien and Charlie Davies forming a new half-back partnership.

Centre Jack Dixon is promoted to the starting line-up in place of injured Tyler Morgan as the Dragons look to snap a three-game losing run at the Principality Stadium.

Newport Gwent Dragons: 15 Carl Meyer, 14 Adam Hughes, 13 Adam Warren, 12 Jack Dixon, 11 Hallam Amos, 10 Angus O'Brien, 9 Charlie Davies; 1 Phil Price, 2 Elliot Dee, 3 Brok Harris, 4 Rynard Landman, 5 Nick Crosswell, 6 Lewis Evans (c), 7 Nic Cudd, 8 Taulupe Faletau.

Replacements: 16 Rhys Buckley, 17 Luke Garrett. 18 Lloyd Fairbrother, 19 Matthew Screech, 20 Ed Jackson, 21 Sarel Pretorius, 22 Dorian Jones, 23 Geraint Rhys Jones.

Scarlets: 15 Michael Collins, 14 Liam Williams, 13 Hadleigh Parkes, 12 Scott Williams, 11 Steff Evans, 10 Steven Shingler, 9 Aled Davies; 1 Rob Evans, 2 Ken Owens (c), 3 Samson Lee, 4 Jake Ball, 5 David Bulbring, 6 Lewis Rawlins, 7 James Davies, 8 John Barclay.

Replacements: 16 Ryan Elias, 17 Dylan Evans, 18 Peter Edwards, 19 Jack Condy, 20 Morgan Allen, 21 Gareth Davies, 22 Aled Thomas, 23 Gareth Owen.