In the above, WB, WC, WE and WF stands for the winners of Groups B, C, E and F, who are the teams that will play the qualifying third-placed sides.
Who plays who is pre-determined, so the final rankings of the table of the best third-placed teams is irrelevant.
As mentioned earlier, those currently going through, in alphabetical order, are third-placed sides from Groups A, C, D and E.
That would lead to these last-16 ties:
WB v 3E
WC v 3D
WE v 3C
WF v 3A