It was a disappointing start to the Olympics for Northern Irish rowers Philip Doyle and Hannah Scott as both failed to qualify from their heats.
Team Ireland's Doyle and partner Ronan Byrne finished fourth in the men's double sculls heats while the Team GB women's quad sculls, featuring Scott, finished third in their heat.
Both will now compete in repechage races to keep alive any hopes of progressing in Tokyo.
Belfast archer Patrick Huston was 25th in qualifying in the men's individual competition and will now face 40th seed Brazil's Marcus D'Almeida in the opening knockout round in the 64-strong event.
Rio Olympian Huston was the leading qualifier of the British trio with James Woodgate in 38th and Tom Hall 48th which combined to leave GB as 10th qualifiers for the team competition.
In Friday's opening rowing action, Banbridge man Doyle and Irish partner Byrne, world championship silver medallists in 2019, always trailed and their sprint finish wasn't enough to to get past Poland, Switzerland or New Zealand. They will try again on Saturday at 01:40 BST.
Scott from Coleraine, in the Team GB women's quad sculls, battled Germany and the Netherlands all the way to the finish but third place means they too will have to go through the repechage on Sunday at 02:50 BST to clinch a place in the final.
Ireland's reigning World Champion in the women's single sculls Sanita Puspure comfortably won her heat to move into the quarter-finals.
In swimming, Ireland's Shane Ryan has opted out of the 100m backstroke to concentrate on the 100m butterfly and the 4x200m freestyle relay.
US-born Ryan's decision was based on persistent shoulder pain he has been experiencing, which is specific to the backstroke and was made in consultation with the Team Ireland swimming and medical staff in Tokyo.