Kuszczak was the first to race up to Cristiano Ronaldo after the final whistle following the winger's brilliant matchwinning free-kick.
"It was a bad mistake for their goal," admitted the Poland keeper.
"You don't expect that kind of thing to happen.
"Everyone could see I ran to Ronaldo at the end to thank him, not just for his goal but the fact that we won.
"The lads helped me feel better afterwards. Everyone makes mistakes, the key is to learn from them."