Standish Leisure Centre shut on Tuesday (December 29) after the worker was informed and told to isolate and sent home.
Leisure centre bosses said they were unable to find another member of staff to cover the shift so they decided to close early.
A spokesman for Inspiring Healthy Lifestyles, the charitable leisure trust which runs health and wellbeing services across the borough on behalf of Wigan Council, said: “A member of staff was contacted while in work and informed that they had been in contact with someone who had since tested positive for coronavirus.
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“The member of staff was told to isolate and sent home. Unfortunately, we were unable to find another member of staff who was available and lived close enough to the Leisure Centre to cover the shift for the last two hours the building was due to be open and took the decision to close early. We apologise for any inconvenience caused.
“Our leisure centres are constantly cleaned during operational hours and deep cleaned at the end of every day. All staff maintain a safe 2m distance and wear face masks when moving around the building.”
They added: “We have extremely safe operating protocols in place and customers can be assured of the very highest safety measures.”