Antrim lost Niall O'Connor to an early red card as their three-year stint in the Leinster Senior Hurling Championship was ended with a 3-15 to 1-16 defeat by Offaly in Tullamore.
Brian Duignan (1-7), Dan Ravenhill (1-2) and Killian Sampson (1-0) scored Offaly's goals to help the Faithful County retain their top-flight championship status for 2026 while condemning Davy Fitzgerald's side to the Joe McDonagh Cup.
Knowing that only victory would keep his team at hurling's top table, Fitzgerald received a pre-match boost when he was able to reinstate James McNaughton and Keelan Molloy to the starting line-up after suspension and injury.
However, having already conceded a second-minute goal from Offaly marksman Brian Duignan, the Ulster county's hopes were further hit when O'Connor was shown a straight red card after just seven minutes at O'Connor Park.
O'Connor was sent off by referee Michael Kennedy, who adjudged that the corner-back had stamped on Offaly forward Charlie Mitchell after consulting with his empires.
It was the third game in a row in which Antrim were reduced to 14 men following Declan McCloskey and McNaughton's dismissals in defeats by Dublin and Galway respectively.
To Antrim's credit, they worked hard to stay in touch after a disastrous start, but Offaly were able to move three clear through Dan Ravenhill's penalty after Mitchell went down in the square under Conal Bohill's challenge.
Antrim, who had the wind advantage in the first half, again showed resilience and levelled the score at 2-4 to 0-10 with four unanswered points, which included two from the returning Molloy.
Offaly, however, finished the half strongly with five of the last six scores to establish a 2-9 to 0-11 cushion at the break.
With Offaly initially unable to capitalise on their wind or numerical advantage, the second half was a low-scoring arm wrestle with the hosts maintaining their four-point lead before McNaughton - who finished with 1-8 - gave Antrim renewed hope with a brilliant goal.
McNaughton's 65th-minute strike brought Antrim back to within one, but after Stephen Rooney immediately denied Duignan with a superb goal-saving block, Sampson's green flag three minutes from time sent Offaly on their way to victory.
Antrim have been the escape artists in Leinster in recent years, earning last-round wins over Westmeath and Carlow in 2023 and 2024 to retain their status, but they drop out of Leinster after losing all five of their matches this year.