Victory over Croatia last month had left Wales in pole position to book their place in Germany next summer heading into the final two qualifiers, but Rob Page's side handed that advantage back as they were held to a draw in Armenia over the weekend.
Croatia meanwhile moved back into second in the group as they eased past Latvia, and they now hold a two-point advantage over Wales. A win will seal qualification, but Wales have a better head-to-head record and so will qualify if they win and Croatia drop any points.
Before Wales can worry about the result between Croatia and Armenia though, they must beat Group D winners Turkey. Fail to do that, or if Croatia do win their match, and it will be the play-offs for the Welsh this time.
How to watch Wales vs Turkey
TV channel: In the UK, the game will be televised live on Viaplay Sports, with a free-to-air broadcast in the Welsh language on S4C.
Live stream: Subscribers can also catch the contest live online via the Viaplay app and website. A free live stream is available in the Welsh language on S4C.
