MODERN PENTATHLON WORLD CHAMPIONSHIPS
Venue: Crystal Palace, London Dates: 13-17 August
Coverage: Watch highlights from 2000 BST on Saturday and Sunday on the red button (Sat only on Freeview) and BBC Sport website (UK users only)
Fell took Olympic silver in Beijing last year
World modern pentathlon number one Heather Fell admitted she was not at her best after reaching Sunday's World Championship final in Crystal Palace.
Fell finished 12th overall, one place ahead of compatriot Katy Livingston in semi-final A, while Olympic champion Lena Schoneborn also went through.
Scots Mhairi Spence and Freyja Prentice secured their places from semi-final B.
Spence won from defending champion Amelie Caze from France while Prentice qualified in 12th place.
"I was a long way off my best and there's definitely room for improvement," said Fell.
"Now I'm in the final, hopefully I can enjoy it and just do my best."
She added: "I'm feeling terrible today, but it was good to be able to take the last lap at a jog.
"I'm going to need as much rest as I can get."
Livingston, who won bronze at the last World Championships, said: "I've achieved the main aim for today and made the final. I'm just not happy with the last event. I just couldn't hit them down today. Hopefully Sunday will be a better day.
"I fenced exactly what I wanted to, 900 is a decent score. Swimming was just off my PB which is pleasing, so hopefully I can go faster in the final. My family are here and that gave me a bit of nerves that spurred me on to swim well.
"I feel physically fit and I'm happy with how I can fence and confident with my riding. My shooting there was disappointing so I need to get in a good position and see what I can do on Sunday."
Hungary's Sarolta Kovacs was first across the finishing line in the run/shoot in semi-final A, despite starting 41 seconds behind Polina Struchtkova of Russia.
But Schonebrun was officially credited with topping the rankings in the semi after her time was adjusted to make up for a problem with her target during her final shoot.