WHAT TIME IS IT?
The match at the Stade de Lyon kicks off on July 7, at 3am (Singapore time).
WHAT IS AT STAKE?
Portugal and Wales are both targeting their first major tournament title. The winners will face either world champions Germany or hosts France in the final.
HAVE THEY MET BEFORE?
This will be the first competitive meeting between the two sides. They have met in three friendly matches, with Portugal winning two and losing one.
WHO ARE THE FAVOURITES?
Portugal are the bookmakers' favourites. They are going into their seventh major semi-final and fourth in the last five European Championships.
Wales, playing in their first major tournament since the 1958 World Cup, are the first team to reach the semi-finals on their debut since Sweden in 1992.
ARE THERE ANY INDIVIDUAL BATTLES OF NOTE?
The clash has been billed as a showdown between Portugal forward Cristiano Ronaldo and Wales forward Gareth Bale.
They are club mates at Real Madrid and won their second Champions League title together with the Spanish giants in May. Some observers believe this duel could determine who wins the 2016 Ballon d'Or for the world player of the year.
HOW HAVE RONALDO AND BALE FARED SO FAR?
Both of them have been directly involved in at least four goals each. Ronaldo has two goals and two assists, while Bale has scored three and assisted two.
ARE BOTH SQUADS AT FULL STRENGTH?
No. Portugal are missing defensive midfielder William Carvalho through suspension. Wales will have to do without defender Ben Davies and midfielder Aaron Ramsey. They are also suspended.