A brace from Nadjim Abdou was not enough to help the Lions keep the pressure on second-placed Peterborough for automatic promotion, as Gary Alexander was sent off for deliberate handball at the Memorial Stadium.
"At one time (Rickie) Lambert looked like scoring from every corner," admitted Jackett. "We couldn't handle his physical presence.
"Now we are certain to be involved in the play-offs and it's all about going into them in good form. One club is going to have a day to remember at Wembley. Why shouldn't it be us?"
Jackett also revealed that referee Phil Gibbs has agreed to review his decision to dismiss Alexander, with the striker facing a three-match ban that would rule him out of one of the play-off semi-finals.
"He insists the ball hit his chest," said Jackett. "The referee has agreed to look at it."