Cup fixture error
Stewart is right, the current situation is unfair on Sergei and needs to be rectified.
Adam, I recommend
(i) Annul the match CAS v GCK, cancel yellow cards, reset ELs etc.
(ii) Schedule the match that should have been, CAS v GTH, for next Tuesday.
(iii) Push the remaining league fixtures back by 7 days.
(iv) Don't beat yourself up about it - you're not the first GM to make such a mistake.
If replaying a single match is not possible, then replay all the QF matches. And I say that even
though it's possible that Colorado's win will be overturned.