The fourth-seeded Antonsen overcame the former world No. 2 21–11, 15–21, 21–16, recovering after losing the second game to seal victory and move within one win of the title.
His victory ended Lee’s impressive run at the tournament, where the Malaysian had already defeated world No. 2 Christo Popov in the quarter-finals.
Antonsen makes commanding start
Antonsen took control early in the opening game, using precise placement and aggressive attacking shots to put Lee under pressure.
The Dane built a substantial lead, moving ahead 13–4 before maintaining his advantage to close out the game 21–11.
Lee struggled to match Antonsen’s consistency during the opening exchanges, but the Malaysian remained determined to turn the contest around.
Lee fights back to force deciding game
Antonsen appeared to be heading towards a straightforward victory after opening the second game with a 4–0 lead.
However, a series of errors allowed Lee back into the contest. The Malaysian gradually raised his level, taking advantage of Antonsen’s dip in performance to draw level at 16–16.
Lee then seized control of the closing exchanges, winning the game 21–15 to force a decider.
The comeback put Antonsen under renewed pressure and ensured the semi-final would be decided in a third game.
Danish star regains control
Antonsen responded positively in the deciding game, beginning with greater intensity and establishing a 9–2 advantage.
The Dane maintained his lead through the middle stages, reaching the interval at 11–5 before continuing to attack as Lee attempted another recovery.
Antonsen’s energy and precision proved decisive in the closing stages. He moved ahead 18–13 and converted his first match point to win the game 21–16, completing the victory in three games.
Tanaka awaits Antonsen in the final
Antonsen will face Japan’s Yushi Tanaka in Sunday’s final after the Japanese player progressed through the other semi-final.
Tanaka’s presence in the final adds another challenge for the Danish star, who will be seeking to convert his strong run into the Arctic Open title.
For Lee, the defeat ends a promising week in Finland. The 2021 All England champion and 2024 Olympic bronze medallist showed signs of returning to his best form after struggling with injuries and inconsistent results in recent seasons.
Antonsen, meanwhile, will head into the final with confidence after surviving a demanding test and demonstrating his ability to recover when the match turned against him.