Parc y Scarlets is being "rapidly" turned into a temporary field hospital that will accommodate 500 beds.
The home of Pro14 region Scarlets in Llanelli is one of several rugby grounds in Wales being converted to help in the fight against coronavirus.
Newport's Rodney Parade stadium has also become a fast-track coronavirus testing location.
The Ospreys training base at Llandarcy is also to be used as a hospital during the crisis.
And the Principality Stadium, the home of Welsh rugby, will serve as a field hospital for up to 2000 patients.
Scarlets making rapid progress
Llanelli is served by the Hywel Da University Health Board who have so far had 54 confirmed cases among Wales' 1,241 coronavirus cases.
Leisure centres and other public buildings in Carmarthenshire will be turned into hospital wards to tackle demand triggered by coronavirus.
Hywel Dda said the steps were essential to managing "patient flow" critical to fighting the virus.
Parc y Scarlets could be fully operational as a hospital within two weeks, if required.
All rugby in Wales is currently suspended, as is the Pro14 competition the Scarlets compete in.
"Things have progressed very quickly, " said Scarlets general manager of rugby Jon Daniels of the adaptations to the ground.
"We are aiming to be close to operational within a couple of weeks. It is a big task and a big challenge, but everyone is pulling in the same direction.
"It is a contingency plan — as with everything with coronavirus, nobody knows how long it is going to last and how bad it could get.
"We are creating somewhere in the region of 400-500 temporary hospital beds. We are creating bays with hospital beds, plumbing, electrics, air-handling units, and also doing the catering for the patients while they are here.
"Potentially, that could be 1500 meals a day being served, it is a big task. There are four kitchens on site and our trained staff — chefs, sous chefs — will be preparing those meals.
"It is hard work what we are doing here, but it is an absolute privilege to serve our community in any way we can."
Rodney Parade 'fundamental'
Newport's Rodney Parade is also set to play a key role in the fight against coronavirus with the Aneurin Bevan University Health Board warning they fear being "overwhelmed" by cases.
Gwent has 32 new cases and 514 in total among 1231 across Wales.
Rodney Parade hosts Dragons and Newport RFC rugby union teams and League Two football side Newport County, but the sports are on hold amid the pandemic.
The health board said the drive-through station was "fundamental" at a time when "the most vulnerable people need us most".
It added the Rodney Parade facility would "help us get our teams back in to work on the frontline".
A Dragons statement said the venue "has been provided free of charge as a base firstly for frontline NHS staff to check if they have the virus and are able to return or continue working on the frontline".
The public have been told the venue is only for NHS staff only.
"Anyone showing symptoms of coronavirus (a high temperature or a new, continuous cough) should contact the NHS 111 service," read the health board's statement.
Dragons managing director Mark Jones said: "The health service and care workers are doing an incredible job in such difficult circumstances, so we are happy to offer our help and support in any way we can.
"Playing our part in the local community is the at heart of what we're about at the Dragons, and in times of crisis people stick together to help their community.
"We would urge everyone to follow the latest NHS advice on protecting themselves from the virus, particularly to stay at home and avoid unnecessary travel."
Ospreys "rooted in community"
The Ospreys training base at Llandarcy Academy of Sport is to be transformed into a field hospital in a bid to deal with the pandemic.
Work has already started at Llandarcy which is part of Neath Port Talbot Council Group of Colleges. It will be completed in the next three to four weeks when beds will be used for COVID-19 patients and other patients who need medical care.
Ospreys Managing Director said it was the least they could do.
"The Ospreys have always been rooted in the community and region," he said, "and we were happy to help in any way to ease the pressure on the NHS and to assist in dealing with coronavirus."
Denbigh Rugby Club has also opened its doors to the NHS.
The League One North team's ground will be a Fever Assessment Centre for Central and South Denbighshire GP practices
President Tegid Phillips said, "As a club we were more than keen to do what we could to contribute to the effort and support the NHS."