Freeman wants Northampton to turn Euro pain into Premiership joy
Saints found themselves 20-3 down against Leinster in the semi-finals of European club rugby union's elite Champions Cup last month, with their Irish opponents being roared on at Dublin's Croke Park.
But Northampton, to their credit, recovered in front of a sell-out crowd of over 82,000 and staged a late rally only to suffer an agonising 20-17 defeat.
Freeman knows the club cannot afford a similarly sluggish start when they face Bath in another sold-out clash at Twickenham
"It (the Leinster loss) got brought up on Monday," said Freeman. "It was on a big stage and we knew how it felt, so it's been about connecting those emotions and not wanting to feel that again."
"Croke Park was a tough arena to go to. The frustrating thing from that game was we could have done it if we had put our game on the park a little bit sooner. If we were more physical from the off, we would have come away with something."
The 23-year-old added: "That gives us confidence going into Saturday - we know that when we get our game right, we are hard to stop.
"We're always learning - there are games that we've won that we've learned from as well. But the two big games at Croke Park and against Harlequins at Twickenham will help us a lot."
Northampton finished top of the regular season Premiership table but the title is decided by two play-off semi-finals and a final.
The Saints have been lauded for their attacking rugby but Freeman insisted defence coach Lee Radford had been crucial in Northampton's rise to genuine title contenders.
"Lee coming in has been a massive help," Freeman said. "He's given us that fight that means we're fighting to the end of every fixture. You saw that at Munster.
"Even when we've been on top of teams, there's been a history of us taking the foot off the gas a little bit and that's changed this season. Now we keep our foot on the gas or claw back if we're behind."