Michael McKillop added a first IPC European Championship gold to his haul of Paralympic and world titles as he won the 800m T38 gold in Swansea.
McKillop's time of 1:58.16 was inside the existing T38 world record although he has run 1:57.17 in T37 competition.
Because McKillop, who has a mild form of cerebral palsy, is classified as a T37 athlete his time will not be recognised as a new T38 world record.
McKillop, 24, will aim for a second gold in Saturday's T38 1500m.
The T38 800m world record of 1:58.87 was set by South Africa's Malcolm Pringle at the 2004 Paralympics in Athens.
McKillop was tracked by Russian Chermen Kobesov over the first lap as he led at the bell in 58.51 but the Irishman pulled away in the second 400m to win by almost eight seconds.
Kobesov took second in a personal best time of 2:06.11 with Ukrainian Valentyn Miedviediev third in 2:16.57.
|MICHAEL MCKILLOP FACTFILE|
|1990: Born, 27 January, Northern Ireland|
|1992: Diagnosed with cerebral palsy at two years of age|
|2006: Wins World Paralympics gold and silver medals aged 16|
|2008: Beijing Paralympic T37 800m champion|
|2009: Irish U20 Cross Country champion|
|2011: Wins World Paralympics 800m and 1500m titles in Christchurch|
|2012: Double gold medallist at London 2012 Paralympics|
|2013: Retains 800m and 1500m World titles in Lyon|
After a year badly affected by a foot injury, an emotional McKillop rated Wednesday's Swansea triumph as "one of the best wins of my career".
The Northern Irishman was unable to run from last autumn until May and McKillop has acknowledged that his morale suffered during his period out.
"Whenever your career is on the line and you come back from such a severe injury it is a historic moment and I am so pleased," said the triple Paralympic champion.
"I got to the bell and kicked and then at 200m to go looked behind and the Russian wasn't near and I was running a quick time.
"That's after four months of training. If I had a full winter I could have run 1:56 but it's not about times, it is about titles.
"We are a small nation, we don't win many medals and it means a lot to the Republic of Ireland and the people of Northern Ireland who have supported me as well."
McKillop, who has a mild form of cerebral palsy, has been unbeaten in Paralympic events since the 2006 IPC World Championships in Assen.
Since then, he has gone on to win three Paralympic gold medals in addition to five world titles.
However prior to Wednesday's race, he had not won a gold medal at the IPC European Championships.
McKillop's talent also enabled him to win the Irish Under-20 Cross Country title in 2009 as he earned a place at the European Cross Country Championships in Dublin where Mo Farah was among the competitors.