Croesyceiliog teammates, Kerry Jenkins and Rhian Wilmott take the half back positions, with Scrum Half, Cath Walkley returning from the 'A' squad to take a place on the bench. Fly half, Awen Thomas is also on the bench following her performance against the French.
Dee Croft earns her first cap replacing Jamie Kift as hooker, following a knee injury earlier in the week.
Props, Dawn Mason and Kath Lenaghan will be under pressure to perform as Amy Broadstock, who received her first cap a fortnight ago, will be eager to play a part in the game.
Louise Rickard, who stars in the BBC2 documentary, 'SAS - Are you tough enough?' on Sunday night, plays at outside centre with Claire Flowers and Sue Jones on the Wings. Naomi Thomas, who has won 'man of the match' in the last two internationals, plays at full back.
National Manager, Gareth Kear commented, "After our first two games, where we won one, lost one, we feel that we have to pull together all the positives from both previous games. We know we have the ability to beat Spain and although it will be a difficult challenge playing in Madrid, if we can stay focused and play to our strengths, it is a game that we can win."
The Game kicks off at 12.30pm on Sunday at the Spanish National ground in Madrid.
1 DAWN MASON 2 JAMIE KIFT 3 KATH LENAGHAN 4 SUE GRAINGER 5 LIZA BURGESS 6 KYLIE WILSON 7 PIP MINTO 8 APRIL DENT 9 KERRY JENKINS 10 RHIAN WILMOTT 11 SUE JONES 12 MELISSA BERRY (CAPT) 13 LOUISE RICKARD 14 CLAIRE FLOWERS 15 NAOMI THOMAS
16 AMY BRAODSTOCK 17 CATRIN EDWARDS 18 JACKIE MORGAN 19 HELEN EDWARDS 20 AWEN THOMAS 21 CATH WALKLEY 22 KAREN MAYZE
Beating Merthyr has boosted Carmarthen Quins hopes of reaching a top eight spot in the Principality Premiership. Quins captain Haydn Pugh is delighted with his team's progress and is determined that everyone from the Under 6s through to the senior team, enjoys the ride.
When the Wales squad were asked to nominate individuals who played a big part in their early playing days, Wales and Dragons full back and wing Hallam Amos thought of his former Monmouth School rugby coach John Bevan.
Sam Cross and Luke Treharne have been named as co-captains of the Wales Sevens side as head coach Gareth Williams names his 12-man squad to play in the first leg of the HSBC World Series in Dubai next weekend.
Bedwas head coach Steve Law and players Nicky Griffiths and Alun Rees extol the virtues of the close knit club as they prepare to host third place RGC 1404 - who are one place head of them on the Principality Premiership points table - on Saturday.
Many of the Wales squad have said Diolch (thank you) to someone who played an important part in their early playing days by nominating them to be invited to the Wales v South Africa match. One person, Gowerton Comprehensive geography teacher Mr Dean Mason was nominated by two of his former pupils, Dan Biggar and Sam Davies.
The second WRU disability rugby pilot has been delivered, this time in Caerphilly schools, culminating in a festival at the Caerphilly Centre of Sporting Excellence, Ystrad Mynach tomorrow. Plans are in place to set up a Disability Rugby Club in Newbridge to provide long-term playing opportunities.
WRU TV: Hear from inside the Wales camp as Neil Jenkins discusses this weekend's clash with South Africa and how the squad are looking to put in a strong performance to round of the 2016 Under Armour Series