But Giggs admitted Williams found it difficult being dropped for such an important fixture, saying: "You're never going to take it well."

On his omission, the 34-year-old Williams said: "He (Giggs) explained it. He's the manager and he makes the decisions.

"It is frustrating but he's the manager and you go with it.

"It's about the squad and when you're called upon. It's always been that.

"Obviously it's disappointing not to play, but you just have to be ready when needed to try and get it over the line."

Williams, who turns 35 in August, is in the final months of his Everton contract and is set to leave Goodison Park this summer.

The former Swansea centre-half has spent the season on loan at Stoke and made 31 appearances for the Sky Bet Championship club.

He has not started for Stoke since a 2-0 league defeat at Hull on February 2, although he did play an hour of Wales' friendly victory over Trinidad & Tobago in Wrexham last Wednesday.

"It's frustrating that I'm not playing at Stoke, but I'll just try and keep doing the best I can," Williams said.

"I want to play and I'll work hard and get back in the team, same here (with Wales) as well.

"It's something that happens to every footballer at some point. I've been fortunate that it hasn't happened up to me until now, but whatever's required, I know only one way to go about my business.

"That's to go to work every day and that's what I'll continue to do."

Giggs fielded an inexperienced side against Slovakia with seven of the starting line-up having won fewer than 10 caps.

Only Bale, Ben Davies, Joe Allen and Wayne Hennessey were in the squad that reached the semi-finals of Euro 2016 in France.

But Williams insists that the youngsters – including Swansea match-winner Daniel James – have proven that they are capable of making their mark at international level.

"There wasn't many caps in our team bar a few players," Williams said. "So all the minutes they can get are important for them going forward.

"We are speaking a lot about the young lads, but it's the whole group they are in.

"We don't need to keep talking (about) whether they are ready. They've proven they can play and they are doing well for their teams every week. They've done the business."

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