Take public transport, advises council ahead of big sports day.
Motorists and visitors to the city centre are being warned to leave plenty of time for their journeys.
Wales take on Italy in their first home game of this year's Six Nation season, with kick-off at 2.30pm and a crowd of 74,000 expected at the game.
Cardiff City are also playing at home, to Norwich City, with a kick-off at 3pm. A crowd of 27,000 is expected.
Cardiff council is advising people to allow plenty of time to get into the city for both events.
A spokeswoman said: "The best way to travel to the event is by public transport and coach wherever possible.
"Those bringing their cars into the city can ease worries over congestion and parking costs by using the council's park and ride service."
Park and ride is available at Cardiff's County Hall (CF10 4UW), the cost is PS6 per car and can be accessed from J33 of the M4.
The drop-off point in the city centre will be Callaghan Square North, in the lay-by next to Eversheds.
The car park will have a staff presence from 8.30am and will open at 9am, with the first bus at 9am.
The last bus will leave the pick-up point at 6pm, with the car park closing at 6.30pm.
Coach parking will be provided off Sophia Close where there are also driver facilities.
The cost is PS10 per coach and the coach park is a five-minute walk from the stadium.
There will be a full road closure from 12:30pm to 5:30pm.
Arriva Trains Wales will be providing extra train services and additional seating capacity where possible to cater for fans travelling to and from the games.
A spokeswoman said: "Train services are expected to be very busy.
"For the return trip, customers are advised to ensure they make their way to Cardiff Central Station with plenty of time to catch services advertised in the normal timetable."