The actor, best known as Ramsay Street's Paul Robinson, shot a kissing scene with Mann over 30 years ago as they appeared on cult series Prisoner together.
At the time, Dennis was playing a teenage guest character - while Mann was portraying the regular role of Doreen Anderson.
Reflecting on the experience, Dennis commented: "I was so nervous, just hopeless. I was surrounded by this bevy of major actresses, really big stars, and here I was in my first significant ongoing role."
Meanwhile, Mann revealed that Dennis used to bounce around the set, explaining: "He couldn't stand still so the director would tell me to follow him around and when he slows down, move in on him for a two shot. I'd have to almost pounce on him - it was quite primal, actually!"
A Neighbours statement said: "It's too early to say if their Neighbours characters will be locking lips in upcoming storylines, however - from the shots posted today - the two seasoned pros are very happy to play up for the cameras if required."
As announced earlier this month, Mann has joined Neighbours to play Kyle Canning's outspoken grandmother Sheila.
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