The Lions were based at the same South Wales hotel as Manchester United before last weekend's FA Cup final and the two Irishmen took the chance to spend some time together.
But Keane left O'Driscoll in no doubt he expects the All Blacks to provide the Lions with the toughest test.
"Roy thinks we are really going to be up against it," said O'Driscoll.
"He's looked at the form the All Blacks are in and knows how rare it is for the Lions to win there, but he'd love to see us win.
"It was great to sit down and talk to him. He is a national icon, a big hero and it's always nice to meet your heroes on a personal level. He is so passionate about winning and that is infectious."
O'Driscoll paid tribute to the part Keane had played in bringing a professional attitude to the Republic football team.
"Not that long ago, it used to be a case with the Irish teams of giving it a lash for an hour and then the floodgates tended to open," O'Driscoll told the Daily Mail.
"Professionalism has helped us close the gap and Roy has been a driving force."