Victoria Catterson broke Michelle Smith's 25-year Irish record as she qualified for the Final of the Women's 200m Freestyle at the Commonwealth Games, while Daniel Wiffen posted the best qualifying time in the Men's 400m Freestyle.
Ards woman Catterson became only the second Irish woman to break the two-minute barrier with a time of 1:59.86 as she finished fourth in her Heat, breaking Smith's previous record, set in 1997, by 0.07 seconds and progressing to the Final.
Grace Davison was eliminated in the same Heat as she touched up in 2:10.00 to miss out on moving on to the next stage, with Australia's Ariarne Titmus setting the time to beat as the leading qualifier with a 1:55.68.
There was disappointment for Bethany Firth, too, as the Seaforde swimmer finished sixth in her Heat in the same event and missed out on qualification for the Final.
Great Britain's most decorated Paralympian of all time clocked a time of 2:08.34, which wasn't enough to see her progress, and she will now turn her attentions to the 200m Freestyle in the S14 category.
Meanwhile, Wiffen got Northern Ireland off to a winning start at the Commonwealth Games in Birmingham as he touched up first in his 400m Freestyle heat to qualify for the Final.
The 21-year-old finished the heat in a time of 3:47.43 to beat Australia’s Mack Horton by 0.11 seconds, which will see him return to the pool later today as favourite for a medal having set the fastest qualifying time.
Kaitlyn McCaw was unable to qualify for the Final of the 100m Butterfly as she finished seventh in her Heat in a time of 1:02.60, while Siomha Nic Bradaigh did not start her 50m Breaststroke Heat.
In the Boxing, John-Paul Hale suffered disappointment as he suffered a majority points loss to Uganda's Joshua Tukamuhebwa in his Round-of-32 match in the light-welterweight division.
The Star ABC man had been backed to do well in Birmingham but instead was subjected to a 3-2 loss on the judges' cards.
Meanwhile, Northern Ireland’s Men’s Triples lawn bowls team got off to an unbeaten start on day one as they defeated the Norfolk Islands 24-10 before drawing 15-15 with Wales.
The team of lead Adam McKeown, second Gary Kelly and skip Ian McClure were down 5-0 after three ends of their match against the Norfolk Islands, but a fine resurgence saw them win 11 of the remaining 15 ends to claim a comfortable victory.
And facing a three-point deficit going into the final end against the Welsh, they produced a crucial three-point end to earn a tie and give themselves a good chance of getting out of Section C if they beat Fiji at 8:30am on Saturday.
In the Women's Singles, Shauna O'Neill was beaten 21-14 by Scotland's Dee Hoggan.
Elsewhere, James Edgar finished 16th in the Men's Triathlon, crossing the line in exactly 53 minutes to end the race 2:26 behind gold medal winner Alex Yee of England.
In the Table Tennis, Northern Ireland suffered a quick defeat to Singapore in their opening Men's Team match in Group 3, with the team of Zak Wilson, Paul McCreery and Owen Catchart failing to win a single leg in a whitewash loss.
Northern Ireland are back in action at 6pm against Barbados.