Italy coach Cesare Prandelli admits Japan ran them very close after their 4-3 Confederations Cup win last night.
The victory sees the Azzurri reach the semifinals.
"We deserved it against Mexico, but struggled like crazy tonight. The humidity is something we have to deal with, as it really is difficult," said Prandelli.
He made a remarkable decision to substitute Alberto Aquilani after just 30 minutes, introducing Sebastian Giovinco.
"We were 2-0 down and in the first 25 minutes didn't know what we were meant to be doing. We got it back on track and then tried to preserve the result because we had run out of gas!
"We had no energy to do anything else at that stage. In those moments you are not clear-headed and struggling to do everything, so you have to be even more focused."