|Welsh Pro12 Judgement Day: Cardiff Blues v Ospreys|
|Date: Saturday, 15 April Venue: Principality Stadium, Cardiff Kick-off: 14:45 BST|
|Coverage: Scrum V Live on BBC Two Wales, BBC Radio Wales, BBC Radio Cymru & BBC Sport website and BBC Sport app, plus live scores online|
|Welsh Pro12 Judgement Day: Newport Gwent Dragons v Scarlets|
|Date: Saturday, 15 April Venue: Principality Stadium, Cardiff Kick-off: 17:15 BST|
|Coverage: Live on S4C, BBC Radio Wales, BBC Radio Cymru & BBC Sport website and BBC Sport app, plus live scores online|
Wales places will be at stake at Saturday's Judgement Day double-header at the Principality Stadium, according to Shane Williams.
Ospreys face Cardiff Blues while Newport Gwent Dragons take on Scarlets in the Pro12.
Record try-scorer Williams says the games will be an opportunity for players to impress ahead of Wales' summer Tests against Tonga and Samoa.
"It's a shop window to get on this tour," Williams said.
"Derbies don't usually need any motivation. It seems to bring out the best in the players and I certainly used to love them and couldn't wait until I played the match.
"It's going to be exciting and the Judgement Day matches have been fantastic in the past and I don't see it being any different on the weekend."
Head coach Warren Gatland leads the British and Irish Lions in New Zealand and will be assisted by Rob Howley and Neil Jenkins while Robin McBryde will coach Wales on their summer tour.
Former Wales and Ospreys wing Williams, who retired from rugby in 2014, could himself feature at the Principality Stadium on Easter weekend.
The 40-year-old has been included in local club Amman United's squad for their final against Caerphilly in the National Bowl competition.
"I had a bang on the jaw a couple of weeks ago in the semi-final, but I've managed to make myself available for this," Williams added.
"My priority is helping Amman get to the final. I've been coaching and helping out and played a number of games and we've been able to do that.
"All credit goes to the lads. They've had a great season, they've worked hard and it's all local lads as well that have really got themselves into this final.
"It's very little to do with me and I keep telling them that really.
"My priority is the lads winning and if they do that without me even getting on the pitch, I'll probably be even happier to be honest with you because they've thoroughly deserved it."