With Mike Phillips on British & Irish Lions duty, Williams will battle it out with Tavis Knoyle in the Far East.
And he is relishing the “huge opportunity” to make a lasting impression.
“We’ve been given a huge opportunity to show how well we can perform in Japan,” said Williams.
“With Mike away, me and Tavis are going on tour looking for some serious game-time.
“It will be really competitive between us but whoever gets the nine jersey will be desperate to keep it.
“Me and Tav are good friends and we enjoy training alongside each other, but we will be pushing each other to make an impact this summer.
“I’m ambitious and I know that all areas of my game can improve.
“I’m sure that the forwards will provide me and the rest of the backs with enough quality ball to really express ourselves.
“The Welsh lads who are with the Lions have had their work cut out in preparing for Australia.
“But I’m sure while we are in Japan they will be looking over their shoulders at us and taking a special interest in who is playing in their position.
“Robin has alluded a lot to the fact that there are 15 boys away with the Lions,” said Williams.
“So this is a massive opportunity for us to express ourselves and show what we can do – especially with places in the autumn squad up for grabs.”
Williams expects to confront a well-drilled Japanese outfit and reckons the challenge will be made all the more difficult by the searing temperatures.
“Japan is a different challenge completely to what we are used to in the Northern Hemisphere and we will have to take a different strategy over there to break them down,” said Williams.
“The humidity and heat will present us with a different challenge, but we will have to overcome that.
“I think the preparations we have put in place so far will stand us in good stead when the first Test comes around on June 8.”
“We are talking about playing rugby in 90 per cent humidity at the hottest part of the day.
“From my memory of the Under-20 World Cup I know we can expect the ball to be wetter than it is in Wales – even when it’s a dry day.
“As a scrum-half, the way I play the game will be greatly affected by the conditions.
“So hopefully training with a slippery ball will put me in the right place when the Tests come around – but there have been a few balls going down in training – I can’t deny that.
“We all know it’s going to be different to handle and hold the ball but we have all welcomed it.
“Hopefully we can get all of our dropped balls out of the way before we get on the plane.
“When we get to Japan we want to be totally focused on our game-plan.
“I’m expecting a tight series and it might not be until the 60th minute when the games really open up.”
