By Richard Clarke in Moscow
A football game often comes down to a couple of key moments. If they don't go your way then you are in trouble.
Take Arsenal's game at CSKA Moscow on Tuesday. The home side had edged the game in the first half and deservedly went ahead through Daniel Carvalho's free-kick. However Arsenal responded in the closing stages and thought they had grabbed a point when Thierry Henry controlled the ball in the area and slotted home at the far post.
The assistant referee raised his flag and, for a second, there was confusion over whether the strike had been penalised for offside. In fact it was chalked off for handball. It is a charge Henry firmly denies.
"At first I thought he'd given an offside and disallowed it," said the 29-year-old. "But to say that I handled it and to give me a yellow card for handball when I didn't is wrong.
"If anyone sees me handle the ball on the TV replay then they should come and tell me.
"Sometimes decisions don't really matter in a game, this one has but we still have two games at home and if we win them then we will go through.
"It has been a long time since we had lost away from home and that played a part in reaching the Final of the Champions League.
"CSKA had a plan and they stuck to it. We play them again very soon and hopefully we can put things right.
"No disrespect to CSKA Moscow, they played some brilliant stuff at times, but they were willing to sit back, defend their one goal.
"We just need to keep our heads up now. We're not in a bad situation like we have been in the past and we have to make sure that we do something about it."