Barrister Karl Finnegan told the Circuit Civil Court that the fall occurred in The Fillies Bar at the racecourse on December 28, 2009, after all afternoon races had been cancelled.
He said Ms McNamara, with friends Angela O'Doherty, Margaret Sheridan and Claire Gorman, had retired to the bar where there was a DJ and dancing had been taking place in a 200sqft tiled alcove.
Ms McNamara claimed to have slipped on a wet patch on the floor and injured her head and broke her left wrist.
Ms McNamara and her friends told the court the floor was wet in places. She had been dancing with a man from Armagh, whom she had never met before or since, and when her feet went from under her he fell on top of her.
She denied having told club director and manager Richard Smyth that the Armagh man had been "very rough" and had been throwing her around the floor when they both fell.
She said they had been dancing normally and suddenly her feet had gone "up in the air" on a wet patch.
Judge Deery said he did not accept that Ms McNamara had blamed the man from Armagh for having roughly thrown her around the dance floor or that she had been dancing over-vigorously.
He said impromptu dancing was permitted on the premises and he was satisfied the club did not have a proper cleaning system in place. The bar and dancing area had been packed to capacity.
Awarding her €28,802 damages against the club he said the manner in which she had fallen was consistent with the floor having been wet.