Tim Murtagh has been given special dispensation to arrive late for Ireland's tour of South Africa later this month, in order to play Middlesex's County Championship decider against Yorkshire at Lord's.
Ireland take on South Africa and Australia in two ODIs at Benoni on September 25 and 27, two days after the conclusion of the final round of Championship fixtures, in which a Middlesex victory would end their 23-year wait for the title.
"This match means a huge amount to both Tim and Middlesex," said Cricket Ireland Performance Director, Richard Holdsworth. "Having played with the club for ten years, it would be the culmination of one of his most fiercely-held ambitions.
"While the remainder of the squad will travel out tomorrow [Saturday], we felt this was an exceptional situation and a game which we should allow Tim to play in.
"There has been a long and mutually beneficial relationship between Middlesex and Ireland, and we felt it would further strengthen our close ties by showing some flexibility on this occasion."
Middlesex have agreed to fly Murtagh out to South Africa as soon as the game finishes, in time for him to join the squad ahead of the first ODI against South Africa on September 25.
Ed Joyce, meanwhile, has withdrawn from the tour after being diagnosed with a progressive knee injury which requires minor surgery.
Joyce, who turns 38 next week, will be replaced in the squad by Leinster Lightning batsman Sean Terry, who made his Ireland debut earlier this summer during the series against Afghanistan.
"It's obviously a blow to lose someone of Ed's calibre, but Sean Terry is a batsman of undoubted promise," said John Bracewell, the head coach. "Given the likely pitch in Benoni, and the likelihood we will facing two majority pace attacks, the selectors felt that Sean was the logical replacement."