Mertesacker struck in their semifinal win over Wigan Athletic.
"I was really happy when I scored," Mertesacker recalled last week. "That was something really special and we took that strength, that mental strength which came back after that goal, to go to the final. But during that game, it felt really strange. It was a quite tough game.
"You expect a lot from yourself, but especially when you play against a Championship side. You drop that five, ten per cent of mental power."
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