The pair were chatting to host Zoe Ball about preparing for the sensual routine, which earned high praise from head judge Shirley Ballas, when the professional dancer dropped the bombshell.
Speaking about how she found the challenge, Gemma, 33, commented: “It was a very hard dance to do and straight from the rehearsal room I was struggling to get it. But I think it went okay on the night.
“I loved it. It was a great song. But it was weird doing it with Aljaž because he’s like my bro.”(sic)
Aljaž then went on to reveal how he got Gemma in a romantic mood for the performance, explaining: “We did crack it.
“It’s one of those, I always try, whenever you do the Rumba, you don’t practice romance in rehearsals.
“You want to make it real and you don’t want to act it so as soon as we heard that, ‘Dancing the Rumba…’ Gemma has one particular person that she always switches on when she hears their name. So I said, two words, and it goes like, ‘Tom Hardy’.”
Gemma blushed as she confessed it was true, laughing: “He said, ‘For this dance I am Tom Hardy’, and I was like, ‘Oh okay’.”
The moment came after Aljaž, 27, halted the show when he was given an early birthday present in the form of his own name tag.
The Slovenian dancer was elated when he found a long piece of card with his name scribbled across it behind the sofa on the BBC Two show.
“Look at it! It’s brilliant!” he exclaimed, leaving the Emmerdale actress speechless with his reaction.
The Strictly Come Dancing finale airs Saturday on BBC One at 6.30pm while It Takes Two airs weekdays on BBC Two at 6.30pm.