He had the assembled media pack giggling away as he told certain newspaper journalists he had been seeing their faces in his sleep, such is the interest around potential transfers at Parkhead.
And it is not only the media he has charmed, but his players, too.
Where they were finding ways to lose under Nancy – and Rodgers to a lesser degree – Celtic’s much-maligned squad are now grinding out results, albeit the 10-man reigning Premiership champions could not beat current leaders Hearts at the weekend.
Nevertheless, the upturn in performances and results since Nancy’s calamitous tenure has been stark, and that is without key starters Alistair Johnston, Cameron Carter-Vickers and Jota.
Midfielder Benjamin Nygren, who scored his 14th goal of the season against Utrecht, was asked about the impact O’Neill has had.
“He’s making a big difference,” the Sweden international said.
“He knows the club, he’s been here. He knows how it works here and he’s loved by everyone around the club.
“I think he brought in a lot of confidence, so we’ve been a lot better since he came back.”