The reigning bronze medalist Jun Woong-tae ranked fourth after the opening fencing event of the modern pentathlon at the Paris Olympics on Thursday.
Jeon went 22-13 in his 35 fencing matches in the men's ranking round and earned 235 points to rank fourth out of 36 athletes.
A win-loss record of 25-10 is worth 250 points. Athletes earn five points for each additional victory and lose five points for each additional defeat beyond the 10th.
Jun won bronze at the 2021 Tokyo Olympics to become the first South Korean pentathlete to reach an Olympic podium. He was in ninth place after the fencing ranking round then.
The men's competition will continue Friday with the semifinals featuring swimming, riding show jumping, laser run, which combines running and shooting, and fencing's bonus round, an elimination tournament featuring 30-second bouts, with athletes seeded by results of the ranking round. Medals will be awarded Saturday, with the finishing positions in the laser run determining medalists.
The one other South Korean in action, Seo Chang-wan, ranked 10th with a 20-15 record.
Ahmed Elgendy of Egypt, the 2021 silver medalist, and Oleksandr Tovkai of Ukraine each went 24-11 for 245 points.
The defending champion from Britain, Joseph Choong, ranked 29th after winning only 14 of his 35 matches. (Yonhap)