Martinez conceded his side were guilty of individual errors as they saw their recent revival brought to a juddering halt.
Tim Howard in particular had a day to forget after giving away the opening penalty then failing to reach a Martin Kelly cross which gifted Fraizer Campbell Palace's second goal. Leon Osman's mistake then allowed Jason Puncheon to set up Yannick Bolasie for Palace's third.
Martinez said: "We wanted to start sharp and to be bright with everything and for the first 15 minutes we looked fresh and scored a very good goal.
"But we didn't really have that drive about us to score a second goal and if we had done so in that period then the game is over.
"The penalty was an incredible reward for Palace and from then on the mental change allowed Palace to have a lot of belief and to change the game.
"It was very uncharacteristic of us to concede three goals with three errors, but even then the character was incredible and we almost managed to get something out of the game."
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