Milan coach Filippo Inzaghi was visibly upset after his side's defeat at Sassuolo on Sunday.
The Italian believes referee Marco Guida took a number of incorrect decisions during the match especially Domenico Berardi's first goal of the game which according to the Italian did not entirely cross the line.
"It's not easy to bounce back when you concede a goal that didn't cross the line," Inzaghi told Sky Sport Italy.
"Also their second goal could have been from an offside so it's not easy. We did well to recover but [Giacomo] Bonaventura was sent off when we were in control.
"His first yellow card was not a yellow card offense and the second one is very questionable. Everything is more difficult when you're down to ten men for thirty minutes so today is not easy to comment on the game.
"We wanted to win but sometimes things happen on the pitch that prevent you from doing so.
"[Change of formation?] It's normal when you're trailing, we opted for a different type of formation."