The Welsh girls were three goals up in the first two and a half minutes and looked secure at 7-3 towards the end of the third period. Then they took their foot off the pedal, allowing Otter to stage a tremendous rally, levelling at 7-7 with goals by Imogen Smith (2), Sarah Rogers and Faye Poole. It needed leading scorer Nia Sanders to come to the rescue for Wanderers. She claimed the winner near the end - and her third goal - to see her side home.
Anna Motley scored six for Sheffield Stingrays, who beat Penguin Emperors 13-5.
Later, English Roses beat Liverpool Water Beatles 11-3, including four goals from Lou Betts. It meant that, whatever the outcome of tomorrow's final matches, Welsh Wanderers, Otter Lutra and the Roses will start next season in Division 2.
Photo (Trevor Hyde): Wanderers' goalkeeper Anna Jenkins-Delf in spectacular action.