With club captain Gerrit-Jan van Velze sidelined with concussion since the first match of the season, new Worcester Director of Rugby felt there was only one man capable of deputising.
Munster and Ireland legend has, like his old pal Peter Stringer, enjoyed something of an Indian summer in the Premiership, and the new Worcester skipper led his side to a crucial bonus point victory over Bristol at Sixways on Saturday evening, moving the Warriors seven points clear of their relegation rivals - and potentially condemning Pat Lam to Championship rugby next season.
O'Callaghan, who turns 38 this month, led from the front in Worcester's 41-24 victory, and reflected on his side's win with BBC Hereford and Worcester after the game:
An understandably excited O'Callaghan was positively lauded by Worcester's fans both during and after the game, with many considering him the driving force behind a monumental victory for the club.
Naturally, none of them want to see O'Callaghan depart Sixways at the end of the season.
well done Capt Fantastic again!!!! Heck of a talisman
— Dale Dyer (@DaleDyer19) March 5, 2017
@docallaghan4 how immense is Donncha?! True leader! Awesome today! #please stay! #cite
— Mike Dennis (@mcdennis1971) March 5, 2017
Donncha O'Callaghan take a bow son #WORvBRI
— The Champ Champs (@GifsRugbyNStuff) March 5, 2017
@docallaghan4 great game today skip!! What an afternoon it was, COYW
— Grant Nisbet (@UncleGW) March 5, 2017
@RugbyWorcs @docallaghan4 @WorcsWarriors Our Capt works sooooo hard, top man!
— Nikki Jamieson (@NikkiJamieson67) March 5, 2017
@docallaghan4 was immense again today !! The man is Benjamin button with an engine to die for !!
— damien grimes (@DamoGrimes) March 5, 2017
@docallaghan4 Excellent day when the team perform around you - please stay!
— Dom Beck Johnson (@dgbeej) March 5, 2017
O'Callaghan's impact on Worcester has been significant. Two weeks ago, Warriors Director of Rugby Gary Gold labelled his display during their victory over Saracens "astonishing."
Prior to Saturday's kickoff with Bristol, it was fullback Chris Pennell who hailed O'Callaghan's role in the club's recent on-field resurgence.
Speaking to the Worcester News, Pennell said:
Donncha is fantastic and has got a lot of experience.
You can see all eyes are on him when he talks to us.
He’s an inspirational guy who leads from the front and is someone who genuinely cares and is easy to follow.
He’s been superb. It was my first week back in training last week with him leading the side and I was hugely impressed and I think he’s fantastic.
One would imagine Pat Lam, and indeed Ian Madigan, are far less enthused by the Donncha renaissance.
