Duckett hit 98 as England raced to 278-4 in reply in another high-octane 'Bazball' batting display, only to sky a ball to David Warner for a comfortable catch.
"At the start of the day I'd have been over the moon if I was offered 98 but falling so close to scoring three figures here at Lord's, yeah I'm obviously gutted about that. But I thought it was certainly my best innings in an England shirt," Duckett told reporters after the close of play.
He said that for him the most important thing was to be true to himself in the way he plays his cricket, which in general entails attacking every ball without fear or favour.
"I'd have been gutted with myself if I'd gone away from it and gone into my shell and gloved one to the keeper behind," he said.
"For three or four overs leading up to that, I felt so comfortable hitting it for ones, and 10 metres either side of him (Warner) there I'd have got a hundred."
"I always make jokes about never leaving the ball and sometimes I don't know how I'm getting runs because of it," he added.
Duckett fell during a wild hour in the middle of the afternoon when Australia seemed to bowl nothing but short aggressive balls and England seemed to do nothing but swing hard at every one of them.
For England's part, that came about all by itself, according to Duckett.
"There wasn't really any discussion. Everyone individually went about it differently," he said.
"It's the way we play our cricket. If they're going to have plans like that and we're going to go in our shells and get bombed out, people round the corner would be going totally against what we do," he said, in a nod to some of the criticism of the team's 'Bazball' style of play named after their coach Brendon McCullum.
Overall, Duckett said he felt that England had had the better day and put themselves back in contention after Australia had looked set to put on a huge first-innings score.
"From a position where they could potentially go on and score 500 I thought we fought back so well," Duckett said.
"I think we're in a great position."
