The British super-middleweight stars will meet in the World Boxing Super Series semi-final in Manchester on February 17.
Groves is also defending his WBA 'super' world title but with Eubank Jr already questioning his mental strength following his Wembley Stadium loss to Carl Froch at the initial press conference, 'The Saint' made it clear he does not have to engage in a psychological war.
"I thought Junior would be much more reserved, play it cool a bit more, keep his cards closer to his chest, but he was already really rattled," Groves exclusively told Sky Sports.
"Maybe for some it wasn't that evident, but there were a few things he bit at and maybe a few things I was saying, he didn't want to hear because there might be some truth in what I said.
"But I am not trying to get under Junior's skin. If that happens, it happens, but I am not trying to and I don't envisage I will, like I knew I would with Froch.
"He [Froch] got professional help for the second one and did a fantastic job. But this time around, I didn't think Junior would care."
Groves, who beat compatriot Jamie Cox in the quarter-finals, also labelled Chris Eubank Sr's role in his son's preparations as "totally irrelevant".
Eubank Sr insists his son does not need a trainer due to the "internal navigation system" he has inherited and with Eubank Jr also using a well-known spar in 2011 to try and wind him up, Groves refused to bite.
"I don't care, he [Eubank Jr] can say anything he wants, he can talk about sparring, he can release footage of it, it doesn't matter," said Groves.
"He could've bashed me from pillar-to-post every time we stepped in the ring, but it doesn't matter. He is not good enough, he's not going to beat me. Sparring is irrelevant, the things he says are irrelevant… his dad is irrelevant.
"The dad wants to nudge him along, but he hasn't fought for an awful long time and the dad had hand-picked opposition for the vast majority of his career, which we all knew.
"He can dine out on it, but don't use it as an excuse or a defence when your son is stepping up for the first time.
"The only things I will need to talk about on Junior is, it will be fun for me to see him conform, to change in the build-up."
— George Groves (@StGeorgeGroves) 28 ноября 2017 г.