Mark English has been ruled out of the IAAF World Indoor Championships in Portland after twisting an ankle.
English has already qualified for the Olympic Games over 800m, and has withdrawn as a precautionary measure with one eye on the outdoor season.
Meanwhile at the GloHealth National Juvenile Indoor Championships in Athlone, Carlow's Molly Scott underlined her potential by smashing the national youth record for 60m and equalling the junior record when running 7.42 seconds.
Multi-eventer Elizabeth Morland also set a record of 5.85m in the U-19 long jump.
Finn Valley's Arlene Crossan showed her versatility by taking gold in both the U-18 400m and long jump, while Ciara Sheehy set a championship best in the U-15 shot put.
Adam Sheridan of Westport did likewise in the U-15 boys' shot-put, throwing 13.82m. Tullamore's Mark Milner set a record in the U-17 boys' 800m of 1:55.03.
At the NCAA Indoor Championships in Alabama, Sarah Collins of Providence College was 12th in the 5,000m final in 16:33.96.
Síofra Cléirigh-Buttner of Villanova missed qualification for the final by just a tenth of a second after running 2:04.77 in her semi-final.
Clonmel native Sean Tobin anchored Ole Miss to third in the distance medley relay with a 3:57.47 1600m leg, while Dubliner Harry Purcell helped Villanova to seventh by running a 48.32-second 400m leg.
At the Trafford 10k in England, Kevin Seaward showed his Olympic preparations are progressing well by recording a personal best of 29:13 to finish fifth.