Manager John Toshack is also sweating on the fitness of Nottingham Forest striker Robert Earnshaw, who damaged a calf in training on Friday morning and is considered very doubtful for the Group Four match.
Toshack was already down to 15 fit outfield players, plus three goalkeepers, when he arrived in Finland on Thursday. That total could be just 13, with the probability that Wales will have only five substitutes.
Sheffield United forward Cotterill headed back to Yorkshire on Friday morning to be with his wife, who is believed to be ill. He had barely been able to unpack before heading back to the airport.
Earnshaw was injured in a training session at the Olympic stadium, and Toshack said: "This seems to be never ending. We lost Danny Gabbidon, Joe Ledley and Sam Ricketts within 24 hours before we left Cardiff.
"Now David has had to go home, and Earnshaw is also a real doubt now. He may be fit enough to sit on the bench.
"My only consolation is that the team I had in my head to play when we left Cardiff is still intact."
Wales will now give Neal Eardley a place in defence, while Blackpool's David Vaughan is likely to play in midfield.