Not sure if a video of this exists, but Tatiana Totmianina and Maxim Marinin had an uncharacteristically poor long program at 2003 Trophee Lalique after winning the short program. They only placed 4th in the segment (placing behind not only Dan and Hao Zhang but also Tiffany Scott/Philip Dulebohn and Anabelle Langlois/Patrice Archetto), winding up 2nd overall.
I have to add, Berezhnaya/Sikharulidze 1997 Worlds debut, they were in third after the short and just had a bad long and went out of the medals
Nancy Kerrigan 1993 LP
I don't recall at the moment a certain competition, but Denis Ten has been in top spots after the SP in many ocasions just to bomb and went down in the standings
Kostner has delivered some absolutely bombtastic freeskates but I don't think any of them came after leading in the SP. I think there was one where she managed one double axel and maybe one triple? I don't think she did much better at the Olympics.
"Michelle would never be caught with sausage grease staining her Vera Wang." - rfisher
Rachael Flatt Skate Canada 2011. Entering the free skate in 3rd place to then place last in the free skate with total score of 128. We had rarely ever seen Rachael flatt fall, but this was a disaster. Only successfully completing one clean triple and a fall on a 2A and 3S
That was also the official end of Flatt being a relevant skater.
The topic is worst ever free skate by a leader after the short program.
The comeback free thread reminded me of another one for this thread - poor Joanna Ng at 1992 Worlds, who went from 2nd in the short to 14th overall. She had been badly injured the day of the free program but decided to try to push on and skate. Unfortunately, she showed that she probably was too injured to skate, as she skated very poorly and it was clear she was in pain.