The 34-year-old left Ewood Park for Spurs in January and has given his new boss Harry Redknapp tips on how to get past the team who are currently battling against relegation
The New Zealand international spent eight years at Ewood Park before making the switch in the January transfer window. And after their defeat to QPR, making it a run of one win in nine games, Spurs could use some more points to keep their bid for Champions League football alive.
"The lads were down after QPR, but you have to go back to basics, get motivated and believe you can do the job," Nelsen told the club's official website.
"You have to take care of your own back yard and that starts against Blackburn. We have to win that game and it’s probably a must-win game for Blackburn as well.
"Blackburn will be really up for it in the position they are in as well. It will be difficult game, we have to be completed ready for it and up for it, and I know we will be.
"There are some really good players there. Junior Hoilett is a fantastic prospect and we all know about Yakubu, he scores goals wherever he goes.
"They have some dangerous players, certainly, but so have we and we have have to look at this game as a potential three points for us.
"It's a huge game for both teams, a must-win."