Joanne Cuddihy has produced a season's best of 51.82 to finish third in round one of the 400m at the IAAF World Track and Field Championships in Daegu, South Korea.
This secures her an automatic qualification place into tomorrow's semi-final at 10.55am Irish time.
Cuddihy executed an excellent race strategy from lane seven and remained composed when Allyson Felix (USA), who ran a storming first 200m from lane five, was up on her shoulder in the early stages of the race.
The Kilkenny woman's time is the fastest that she has run in four years. Cuddihy also made the semi-final at the World championships in 2007.
"I really enjoyed that," she said. "It was one of my most exciting races."
Jason Smyth (City of Derry) was also on the track in the 100m in the afternoon session.
Smyth finished in fifth with a time of 10.57 in heat two into a -1.7 wind. This is outside his personal best of 10.22 which he set this year and he will not progress to the semi-finals.
"I was coming up against the best athletes in the world but I would have expected to run faster than that," said Smyth, who won gold in the T13 100m and 200m at the Beijing Olympics in 2008.
"But for me coming to these championships is about seeing what it's like to compete with the big boys."
Tori Pena (Finn Valley AC), who has improved the Irish Pole Vault record six times this season, will compete in the qualification round tomorrow at 1:30am Irish time.
The qualification standard to the final is 4.60m or top 12 performers in qualifying.
