Paul Pollock booked his place at next month's European Indoors with victory in the 3,000m at the Irish Indoor Championships in Athlone on Sunday.
However, the Holywood doctor is a doubt for the Prague event because of an ankle injury.
Letterkenny man Mark English wrapped up his preparations for Prague by clocking 1.51.34 for 800m gold.
Derry's Adam McMullen has also qualified for the Europeans with a new Irish record of 7.80m in the long jump.
Ballymena & Antrim pair Christine McMahon (400m) and Claire Wilkinson took (pole vault) secured gold.
McMahon posted 55.06 to take the 400m title, while clubmate Wilkinson earned pole vault gold with a best of 3.65m.
Pollock, who gained the qualification standard last month, pounced with a lap and a half remaining to grab the national title in 8:09.81.
He revealed that he picked up the injury last weekend, which has cast some doubt on his participation in Prague.
"I will have to see how my ankle is, I injured it last week, so I will have to asses it over the next two days," said Pollock.
"I want to try and make it through to the final in Prague and hopefully I can do that."
English brought his preparations for Prague to a close with a tough victory after a tussle with Waterford man Niall Tuohy.
Declan Murray controlled the 800m before Tuohy barged English on his way to the front of the race.
English displayed his typical finishing speed on the final lap, before easing out on the home straight to take gold in 1:51.34 ahead of Murray and Tuohy.