I always had problems with 4-5-1 Flat. 3-5-2 flat gave me awful result. 4-5-1V did not give me any comfort. We had equal game with 3-3 shots on goal. But suddenly my DMC gets yellow card and I decided to substitute it with MC on 68th minute and change tactics to defensive with counters.
DL--DC----DC--DR
------------------
----MC-MC-MC---
AML----------AMR
--------ST-------

Terrific change in game. Shots on goal 3-11 after 68th minute. And I scored 3 goals within 7 minutes.
My opponent did not have no injuries, no illegal formation. The only change was my DMC out and my MC in. And my DMC was stronger than new MC.