Richard Collins, the finance director at Musgrave-owned Superquinn, has defected to Dunnes Stores just as the chain is poised to be rebranded as SuperValu.
The departure of Mr Collins also comes as the country's top retailers battle it out for Christmas supremacy.
Mr Collins joined Superquinn in 2005, just after it was bought out from the Quinn family by a consortium of investors, including developer Bernard McNamara, in a €450m deal.
Cork-based Musgrave, the family owned business headed by Chris Martin that controls the SuperValu chain as well as Centra, bought Superquinn from receivers in 2011 for about €250m.
Later that year Musgrave established a new entity, Musgrave Operating Partners Ireland (MOPI), to run its Superquinn arm.
That saw Eoin McCormack, previously the trading and marketing director of Musgrave Wholesale Partners, take on the mantle of trading and marketing director at the new subsidiary.
Richard Collins was made finance director of MOPI, and Clare Leonard was appointed HR and operations director.
In August, Musgrave announced it was going to get rid of the Superquinn name and rebrand the 24 outlets as SuperValu. The change will come into effect in February.
Musgrave also said the rebranding would result in 102 staff at Superquinn's support office in Lucan, Co Dublin, losing their jobs by the beginning of 2015.
Dunnes has recently appointed Joe Webb, the former chief executive of Independent News & Media's Irish arm, to its ranks. He's reportedly joining the retailer as its chief financial officer, where he'll work closely with chief executive Margaret Heffernan and her brother Frank Dunne. Within the retail trade, Dunnes Stores is famously known for the musical chairs among its senior echelons. It's also currently seeking voluntary redundancies at its head office and at store level.
In 2011, the managing director of DCC-owned Allied Foods, John Casey, joined Dunnes as supply chain and corporate services director. He left in 2012 and is now managing partner at investment firm Donworth Capital.
That same year, Dunnes' head of buying, Sheena Forde, also left the retailer.
She had joined from Superquinn in 2010 where she was development director. Last year, she joined Musgrave as commercial director of its wholesale partners division.
James Wilson, who was second in command at Superquinn, left there in 2010 to join Dunnes. He's food director at the group.
According to data from research group Kantar Worldpanel, Dunnes Stores is the second-biggest player in Ireland's multi-billion euro grocery market, with a 23.6pc share. Tesco has 26.5pc, but its sales have been falling sharply.
Industry sources reckon that between them, Aldi and Lidl control about 20pc of the market here -- much more than the combined 13.7pc share that Kantar figures suggest.