So far we have two of the eight Round of 16 clashes confirmed:
Switzerland v Poland, Sunday
Italy v Spain, Tuesday
Here is how the other six clashes will decided:
Wales v Third place team
Wales will play a third-place team from either Group A (Albania), Group C (Northern Ireland) or Group D (Turkey).
England v Group F runners-up
England will play the Group F runners-up - either Hungary, Iceland, Portugal or Austria.
Croatia v Third-place team
Croatia will play a third-place team from either Group B (Slovakia), Group E (Sweden or Republic of Ireland) or Group F (either Portugal, Iceland or Hungary).
France v third-place team
France will play a third-place finisher from either Group C (Northern Ireland), Group D (Turkey) or Group E (Belgium, Republic of Ireland or Sweden).
Germany v third-place team
Germany, after topping group C will play, the third-place finisher from either Group A (Albania), Group B (Slovakia) or Group F (either Portugal, Iceland or Hungary.
Yet to be seen
Finally, the winner of Group F (either Hungary, Iceland or Portugal) will play the Group E's runner-up (either Belgium, Republic of Ireland, Italy or Sweden).
What decides the final pairings:
With four matches remaining in the group stages, the playoff picture still has a lot of wiggle room.
The group E third-place finisher will be dependent on the result of Italy v Republic of Ireland and Sweden v Belgium, both of which take place tomorrow.
The group F winner and third-place finisher will be decided after Hungary play Portugal and Iceland play Austria, both fixtures also tomorrow.
Who are the likely third place finishers?
Group A
Albania beat Romania on Monday to secure third place.
Group B
Slovakia drew with England to secure third place.
Group C
Northern Ireland finished third after Ukraine lost all three of their matches.
Their 2-0 win over Ukraine gave the team their only points of the group stages, but that, combined with their goal difference of 0, means they have a better record than both Albania and Turkey, who finished in third place in groups A and D respectively.
Group D
Turkey defeated Czech Republic on Wednesday to finish third.
Group E
This one is out of Republic of Ireland, Sweden or Belgium. Republic of Ireland must get a better result against Italy than Sweden manage against Belgium.
If Ireland and Sweden both win, second place will come down to goal difference between the two and Belgium will be eliminated. If Ireland and Sweden both lose, goal difference will determine who finishes third and who is fourth.
Belgium will finish third if they lose to Sweden and Ireland lose to Italy.
Group F
Portugal are currently third and will stay there unless they beat leaders Hungary.
If Portugal win, Hungary will be waiting on the result of the game between Iceland and Austria. If Iceland win Hungary will finish third; a draw would leave Iceland third; while an Austria win would put Hungary second and send Iceland home.
But there are 12 teams left and only 4 more knockout spots?
The majority of these spots will be filled with third-place finishers, with spaces open for the Group F winner and the Group E runner-up.
Only the top four third-place finishers will advance to the knockout stage.
These four are decided on points. However, if points are tied, it comes down to goal difference, then goals scored, then fair play rankings from the group and finally UEFA national team coefficient rankings if they still can not be decided.
Contenders for the remaining third-place spots are Slovakia, Northern Ireland, Albania, Portugal, Sweden and possibly Hungary who can slip no lower than third in their group.
How the third-place table is shaping up
1. Slovakia - Played 3, goal difference of 0, 4 points
2. Northern Ireland - Played 3, goal difference of 0, 4 points
3. Albania - Played 3, goal difference of -2, 3 points
4. Portugal - Played 2, goal difference of 0, 2 points
5. Sweden - Played 2, goal difference of -1, 1 point
If that doesn't make any sense, check back in tomorrow morning when all the group games will be completed.
