|European Champions Cup|
|Venue: Liberty Stadium Date: Saturday, 13 January Kick-off: 19:45 GMT|
|Coverage: Live commentary on BBC Radio Wales, BBC Radio 5 live sports extra, Radio Cymru and live score updates on the BBC Sport website and app|
Wales international Liam Williams starts for the first time since November as Saracens face Ospreys in a crucial Champions Cup encounter.
The reigning champions also include England forwards Maro Itoje and Billy Vunipola in a strong-looking pack.
Ospreys captain Alun Wyn Jones starts after taking a blow in the Pro14 win over Cardiff Blues, as does centre Owen Watkin.
The Welsh region are second in pool two, two points ahead of Saracens.
Both teams trail runaway leaders Clermont Auvergne who play struggling Northampton at Franklin’s Gardens.
Williams was declared fit after being sidelined since sustaining a groin injury playing for Wales against Georgia on November 18.
Itoje and Billy Vunipola returned to action this month after injury lay-offs.
Jones took a blow to the head in Ospreys’ win over Blues, while Watkin was taken to hospital as a precaution after suffering a knock on the neck and being stretchered off.
Saracens face bottom team Northampton at home in their final pool match while Ospreys will face a tough trip to Clermont.
Sarries beat Ospreys 34-32 when the teams met in October, and Ospreys coach Steve Tandy believes that match can inspire his side.
“It was a great contest up at theirs. We left with two points in the bag, and we have to really step up again on Saturday night,” he said.
“We’re at home, there’ll be a good crowd behind us, these are the occasions that we all want to be involved in. It’s a fantastic opportunity for the boys involved to go out on a big stage and show what they can do.”
|Champions Cup Pool Two|
Saracens, European champions in 2016 and 2017, will effectively see hat-trick hopes disappear if they fail to beat the Ospreys.
Successive pool two defeats against Clermont last month have left Sarries in danger of pool-stage elimination for the first time since 2011.
“It is the first time for a few years we’ve been in a fifth pool match where everything is on the line,” said director of rugby Mark McCall.
“It’s a new experience for us even to be in that position so early in the competition. It is what it is.
“The players want to be involved in quarter-finals, they want to be involved in those games. If we lose, we won’t be. It’s as simple as that really.”
Ospreys: S Davies; Hassler, Beck, Watkin, D Evans; Biggar, Webb; Smith, Baldwin, Arhip, B Davies, AW Jones (Capt), Cracknell, Tipuric, McCusker
Replacements: Otten, Thomas, Fia, Beard, W Jones, Habberfield, Fonotia, Howells.
Saracens: Goode; Maitland, Marcelo, Barritt, Williams; Farrell, Wigglesworth; Vunipola, George, Koch, Itoje, Skelton, Rhodes, Wray, Vunipola
Replacements: Tolofua, Barrington, Figallo, Kruis, Clark, Spencer, Lozowski, Wyles
Referee: John Lacey (Ireland)
Assistant referees: David Wilkinson (Ireland), Eddie Hogan O’Connell (Ireland)
TMO: Kevin Beggs (Ireland)