The 30-year-old Irishman suffered demotion with Blackburn 10 years ago, and spent two seasons in the Championship. Duff and his team-mates head into Monday night's derby clash with Middlesbrough knowing the club could drop out of the Barclays Premier League.
He said: "I got relegated with Blackburn. I'm not sure how many of the other lads in the dressing room have, but it's not a nice feeling to have, and it was the lowest point of my career."
He added: "I don't want it to happen again, so I will be doing everything I can - and I'm sure the other lads will as well - to keep us up."
Sunday's 3-0 defeat at Liverpool and Hull's 1-0 reverse at Aston Villa left the two sides straddling the drop zone with the Magpies three points adrift of the Tigers with just three games to play.
Alan Shearer and his players will hope the gap remains the same after Phil Brown's men have hosted Stoke on Saturday, while defeat for arch-rivals Sunderland at Bolton would keep them in touch too.
However, whatever happens elsewhere over the weekend, Newcastle know they have no option but to beat Boro, who have drawn on their last four visits to St James' Park, and Fulham a week later if they are to stand a chance of avoiding the drop.
Duff, who won two titles during his time at Chelsea and represented the Republic of Ireland at the 2002 World Cup finals in the Far East, admits the game will be one of the biggest of his career.
He said: "This game is huge and we are going to need all of the fans right behind us again.
"It doesn't come much bigger for me personally - it's one of the biggest games I have been involved with in my whole career."