Spain beat Albania 1-0 in Dusseldorf to secure progress as winners of Group B, which in turn meant England would be set for one of the four slots for a team who finished third.
That result also saw France and the Netherlands guaranteed to progress no matter what the outcome of their last Group D fixtures on Tuesday night.
England – who have four points already, so cannot finish lower than third – can win Group C if they beat Slovenia in Cologne and could also finish top with a draw should Denmark not beat Serbia.
Should England draw while Denmark win, then rankings for the top two slots would be decided on overall goal difference, then overall goals scored and then disciplinary points.
Any side which finishes in third place with a better record than three points and a goal difference of minus three will progress into the knockout stage.
If England do go through as winners of Group C, then their last 16 tie will be in Gelsenkirchen on Sunday, against a third-placed team from either Group D, E or F.
In Group D, Austria are currently third ahead of their final game against the Netherlands. However, in Group E, all four teams – Romania, Belgium, Slovakia and Ukraine – have three points. In Group F, the Czech Republic sit third, level on points with minnows Georgia, but with a better goal difference.
Should England finish second in Group C, then they will take on hosts Germany in Dortmund on Saturday.
Were Southgate’s side to end up third in the table, they would play either Group F winners Portugal in Frankfurt on July 1 or the yet-to-be-decided winners of Group E in Munich the following day.
