With England one-up through Wayne Rooney's stunning volley, the stand-in skipper had a wonderful opportunity to extend his side's lead five minutes after the break.
"I had a glorious chance at 1-0 - which I should have scored - but we let them back in the game and that gave them the momentum to get a second," said the Liverpool midfielder.
"We knew it would be difficult, but 1-1 would have done us. They got confidence from the penalty and obviously they were on the front foot and put us under a lot of pressure."
Gerrard thought the penalty, given against Rooney despite TV replays showing the foul to be outside of the box, was the critical part of the game.
"We had the game exactly where we wanted it," he said. "They were running out of ideas - then came the big turning point and we had a mad, crazy five minutes.
"We were controlling the game - and, although they had a lot of possession, we should have gone on and won the game.
"We said at half-time 'let's keep a clean sheet and we are through'."