Now the former Magpies manager returns to St James' Park for competitive action for the first time since his departure next month.
Shearer said: "Kevin will get the reception he deserves. People still love him up here, and rightly so.
"Everybody must be aware of my feelings and respect for Kevin Keegan, and I still speak to him on a regular basis."
He told the Evening Chronicle: "He always said he would only come back for Peter Beardsley's testimonial but now he has no choice.
"We watched Manchester City beat Ipswich on TV on our team bus coming up from Peterborough, and they really played well."
Keegan will be backing Newcastle to go all the way and win the trophy if City fail to beat them next month.
Keegan said: "I have a lot of friends in Newcastle - and win, lose or draw I will shake hands with Bobby Robson after the game.
"If we lose I will tell Bobby I hope they go on and win the FA Cup - and I mean that. I think their fans deserve it more than any other supporters in the country."