Sonia O'Sullivan led the praise after Portaferry runner Ciara Mageean became the first Irishwoman to record a sub two-minute 800m.
Mageean posted a new national record and of 1:59.69 in Bern, Switzerland, on Friday.
It was the 28-year-old's first race since February because of the coronavirus pandemic.
She claimed the gold medal after finishing ahead of Norway’s Hedda Hynne and Frenchwoman Renelle Lamote.
The Irish record was previously held by Rose-Anne Galligan (2:00.58) which was set at the London Anniversary Games in 2013.
Mageean tweeted: "I am absolutely delighted. With the disappointment of everything this year, Olympics postponed and lockdown for months, my coach, my team mates and I put our heads down and worked hard.
"Devastated I won't run for Ireland this year but I'll continue to work and build on this for 2021 and beyond.
"Only the beginning of the few races I'll run this season bt I'm so grateful for the support of my coach @stevevernonrun and @TeamNBMCR team mates and everyone back home."
Irish running legend O'Sullivan added her congratulations on Twitter.
She said: "Congratulations @ciaramageean first Irish woman sub 2mins for 800m. 2020 is a year to back yourself and just go for it."
It is the latest impressive time from Mageean who shattered her own Northern Ireland senior 3000m record back in February at the AIT International Grand Prix.
The Portaferry runner starred with a time of 8:48.27.
Mageean claimed the stadium record and a massive personal best in a hotly contested race against Great Britain’s Rosie Clarke.
