Belfast boxer Aidan Walsh is guaranteed at least a bronze medal at the Tokyo Olympics after defeating Merven Clair of Mauritius in his quarter-final.
The Team Ireland fighter won his last-eight contest in the welterweight division on a split decision.
Walsh, 24, won the first round on all five judges' scorecards and while his opponent battled back, the decision was awarded to Walsh on a 4-1 outcome.
Walsh will fight Great Britain's Pat McCormack in his semi-final on Sunday.
- GB's McCormack & Whittaker secure boxing medals
- McIlroy and Lowry move into contention
Number one seed McCormack has previously beaten Walsh at the Commonwealth Games, World Championship and European qualifiers.
Walsh was composed throughout his quarter-final, repeatedly catching his opponent on the counter and landing some punishing straight right hands.
Southpaw Clair had occasional joy with his looser style but Walsh was able to sit back and pick off his opponent in the second and third.
Three judges gave the fight 30-27 to Walsh, one 29-28 and the last scored it 29-28 to Clair.
Team Ireland's previous two medal successes had come in rowing - a bronze for the women's lightweight four and gold for Paul O'Donovan and Fintan McCarthy in the lightweight men's double sculls.
Harrington and Barr progress
In boxing, Ireland's number one seed in the women's lightweight division, Kellie Harrington, made it through her round of 16 bout against Italy's Rebecca Nicoli on a unanimous decision.
Irish athlete Thomas Barr progressed to the semi-finals of the 400m hurdles, finishing second in his heat behind world-record holder Karsten Warholm.
Barr, who finished fourth in the Rio 2016 Games, clocked 49.02 compared to Warholm's winning time of 48.65.
The Irish runner was the 11th fastest of the 23 qualifiers and will go in the second semi-final at 11.15 BST on Sunday.
Nadia Power, Louise Shanahan and Siofra Cleirigh Buttner were all in action in the 800m heats, but all three of them finished seventh in their races and bowed out.
Shanahan was the fastest of the three but her time of 2:03.57 was not enough to see her progress.
In sailing, Annalise Murphy will not repeat her Rio 2016 heroics after missing out on the Laser Radial medal race.
The silver medallist from four years ago came into Friday's final two races in 14th, having made up ground after a slow start to the week.
However, Murphy was unable to force her way into the top 10, with finishes of 30th place (after a penalty turn) and 40th meaning the 31-year-old from Dublin finished in 14th overall after 10 races.
Irish rower Sanita Puspure withdrew from the single sculls B final, revealing that she has been unwell for several days.
Puspure was expected to challenge for a medal in Tokyo but trailed home in fifth place in her semi-final.
- Five new sports at Tokyo 2020: Everything you need to know about the events
- The fight for our attention: How can sport broadcasters make themselves the most attractive option?