The pair faced off regularly in the SANFL over the past five years but will enter the 2020 season as teammates, following Frampton’s move from Port Adelaide in October.
Despite some heated contests in the State League, O’Brien was full of praise for the 23-year-old.
“We get along really well, he’s a really funny guy,” O’Brien told AFC Media.
“He’s a very good player, very good mark, really athletic and quick.
“He’s another challenge at training.”
But before Frampton joined Adelaide, what exactly did O’Brien think of the West Australian?
“I didn’t really like him on the field when he was at Port Adelaide… he was always a bit lippy.” O’Brien said.
“All water under the bridge now, it’s quite funny reminiscing on the games we played.”
Frampton hasn’t been shy reminding O’Brien about several of their past matchups.
“We had a few good battles in the SANFL,” O’Brien said.
“He keeps bringing up the day he had 28 (hitouts) and 16 marks against me at Woodville.
“Then I bring up my good games against him.”
Adelaide’s ruck department has undergone a significant change over the recent off-season, with veteran Sam Jacobs and rookie Paul Hunter both departing.
2020 marks the first pre-season O’Brien has undertaken without the tutelage of Jacobs.
“It is a bit different, just in terms of training,” he said.
“I’ve always set myself on being able to challenge Sauce and to learn a lot from him at training.
“(Now) I do a lot of work with Frampton and Kieran Strachan, who are both really competitive.
“Elliott Himmelberg when he’s out there as well, the four of do work with Doc Clarke and really challenge each other.”