The jump up to the half marathon didn't go quite as planned for the 23-year-old Norwegian track star.

Making his debut at the men's half marathon distance on Sunday morning in Denmark at the Copenhagen Half, Jakob Ingebrigtsen struggled after trying to keep up with the leaders through 10k, and he would eventually fall back and cross the finish line in 63:13 for 34th place.

Ingebrigtsen stopped after surging through the 10k mark in 27:27, looking as if he was going to drop out. Instead, he began a mixture of running and walking, and would continue on to the finish line.

Meanwhile, the rest of the talented Copenhagen field chased after a quick mark as World Road Running champion Sebastian Sawe out-kicked half marathon world record holder Jacob Kiplimo for the win in 58:05.

• Subscribe To FloTrack To Watch More Track & Field Meets All Year Long
• Watch The Diamond League Live On FloTrack, Starting In 2025
• Jakob Ingebrigtsen, Julien Alfred Cap Season With Diamond League Titles

Rumors circulated earlier in the week that Ingebrigtsen would compete in Copenhagen less than two days after winning the men's 1,500m Diamond League final in Brussels, and the speculation was confirmed by race organizers on Saturday. In an Instagram post with a picture of his Copenhagen Half race bib, Ingebrigtsen said, "The season is not over yet."

Though Ingebrigtsen kept with the lead group and pacers up until 10k, he never looked truly comfortable. He appeared to be grimacing and breathing heavily at times, and when he stopped just past the 10k mark, Ingebrigtsen put his hands on his knees.

Ingebrigtsen is the world record holder in three track events -- the 2,000m, 3,000m and 2-mile -- but he said himself that he doesn't run more than 20k in training, according to race commentators. 

But for the men up front, it was quite the battle. Essentially a four-man race for a good portion of the distance, Kiplimo, Sawe, Isaia Lasoi and Amos Kurgat stuck with the pace set primarily by Olympic 10,000m silver medalist Berihu Aregawi. Aregawi kept the men hovering around 58:00 pace before peeling off before the 15k mark.

Over the final five kilometers, it came down to Kiplimo, Sawe and Lasoi, and with less than a kilometer to go, Sawe was able to put a gap on his competitors to win in 58:05.

Kiplimo notably went down the other side of a median from Sawe in the final meters of the race, and then had to hop back over behind Sawe and finished in second in 58:09.

In information from race organizers in the lead up, the men's pace was originally set to be closer to world record pace -- the record held by Kiplimo sits at 57:31. However, the pacers and front runners kept closer to 58:00 pace.

The women's race also saw a quick finish as Margaret Chelimo Kipkemboi nearly broke the event record, finishing first in 65:11. The 2023 Valencia Half Marathon winner added yet another win to her belt in her first half since finishing fourth in the Ras Al Khaimah Half Mararthon earlier this year.