SC Olhanense travelled to third placed Real SC (Sintra) for their first Campeonato Portugal game under new manager Vasco Faísca who gave debuts to new signings, keeper Cléber and midfielder Muscat.
Olhanense dominated the first-half but wasted several gilt-edged opportunities including a penalty miss by Stevy Okitokandjo.
The visitors paid a high price for their failed attempts when Gustavo Cazonatti headed home the winning goal midway through the second period.
Olhanense remain in sixth place knowing that they must win at home on Sunday against Olímpico do Montijo to retain any chance of getting into the play-offs.
The team will return to the newly-refurbished José Arcanjo Stadium after an absence of over two months. Kick-off is at 3pm.
Photo: Renovated pitch and refurbished terracing