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  Belgium, ranked second in the world, are the next test for Chris Coleman's side as they look to continue their remarkable progress in France.
  Legendary Wales strikers Dean Saunders and John Hartson, who between them won 126 caps and scored 36 goals for their country, explain how Wales can win and book a place in the semi-finals.
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  Saunders: Belgium are going to dominate possession, which is fine, but we have got to stop them from hurting us - that is difficult because they have so many different weapons in their attack.
  We will have to close down Kevin de Bruyne, who has been playing behind Romelu Lukaku and has got a stinging shot in him on either foot, but if Eden Hazard is fit then he will be Belgium's most dangerous player.
  When we beat Belgium in Cardiff in June, Coleman kept Hazard quiet by bringing in Jazz Richards at right wing-back and moving Chris Gunter infield to be the right-sided centre-half in our back three.
  Between them, they handled him really well down Belgium's left, but I don't see Chris doing the same this time because continuity has been a big part of why we have done so well in France, especially at the back where we have been unchanged in all four games.
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  I can see Chris sticking with the same team that started against Northern Ireland, but our right-sided defensive midfielder - either Joe Allen or Joe Ledley - will have to get across to help Gunter as soon as Hazard gets the ball, along with James Chester, the right-sided centre-half.
  Their job will be to stop Hazard from coming inside and to show him down the line instead. When that happens, Gunter will also try to stop the cross from coming in, but you have to be realistic - Hazard is so good, he is going to get some balls over.
  So all our midfield players will have to pick their runners up around the box, not just De Bruyne, and the most important thing will be to mark Lukaku tightly because he will be trying to get between our other two centre-halves when the cross comes in.
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  Saunders: When we clear those crosses, we have got to counter-attack like I know we can do, because while Hazard's attacking play is one of Belgium's strengths, it is also a weakness.
  Jan Vertonghen's injury means we do not know who will play as Belgium's left-back against Wales but, whoever it is, we will be able to isolate them because Hazard does not run back.
  Hungary did it effectively, and they do not have the same attacking threat as us.
  The mistake they made was leaving their wide players too far up the pitch and that allowed Hazard to hurt them more - he was on fire in that game and Belgium should have won by more than 4-0.
  After watching that game again on Wednesday, though, I now have a clearer picture of what Wales will have to do to win.
  There is no way we will be as open as Hungary were from the start because we have so many unselfish and disciplined players like Allen and Ledley who do a lot of running just to support our defenders and ensure we do not lose our shape.
  But, when we steal the ball back, we have to use it properly. That starts with the first header clear from one of those Hazard crosses.
  I would be telling Gareth Bale or Aaron Ramsey to drift over to Belgium's left where they will have space - and the aim should be to get the ball to them and build the attack from there.
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  Hartson: There is a decision to be made up front because Hal Robson-Kanu played in both games against Belgium in the qualifiers and did not let us down.
  Hal is very mobile and gives us a threat in behind their defence with his pace, and he can also carry the ball better than Sam Vokes can.
  Sam is a big centre-forward that you can hit the ball to, and he will keep hold of it. He has a similar role to the one I had up front for Wales - winning headers and winning fouls so the team can advance up the pitch.
  It depends which way Chris wants to go, but Sam has started the past two games and I don't think he has done an awful lot wrong.
  He will contain both of Belgium's centre-halves like he did against Russia and give them problems in the air and on the ground - you cannot get around him.
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  Sam missed a good chance against Northern Ireland but the next one he gets like that, he will put it away. I have worked with him and I know how good he is.
  I also think he will now be feeling like the Wales number nine, not a bit-part player, which is something else I can relate to.
  At first I was always behind Ian Rush, Mark Hughes and Dean Saunders, but when Hughes became manager he made me first choice and my confidence went through the roof.
  I took on the mantle of being the main striker and I think Sam is in that position now, as an important member of this team.
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  Hartson: Coleman has got pretty much every tactical and selection issue right at this tournament so far but we have to appreciate how good this Belgium team is and what an incredible victory this would be.
  For it to happen, we need to have total focus at the back and we will rely on our best two players again - Ramsey and Bale, who have been involved in every Wales goal at this tournament - if we are going to score.
  I am optimistic we can get through, but I would not say I was overly confident about it because watching Belgium the other night was frightening, even if it was only against Hungary.
  One big factor in our favour is that we are unbeaten in our past three meetings, including a win - so we do know how to get a result against them.
  Saunders: Belgium are favourites for a reason but we have a good record against them, even going back to when I was in the team.
  Wales have a winning formula and Bale is part of that. He is a proper match-winner and, for me, the best player in the tournament. With him in the team, anything is possible.
  Pick the XI that you think can take Wales far at Euro 2016 - and then share it with your friends using our team selector.
summary: Wales are the only home nation left in Euro 2016 and are in the last eight at the finals of a major tournament for the first time since 1958.