Rugby fans could face train delays as long as three hours following Australia's world cup tie against Fiji.
Yet another big turn out is expected for what will be tournament's third game at The Millennium Stadium in Cardiff – with thousands expected to make the journey to the Welsh capital by rail.
But supporters going to the match, which kicks off at 4.45pm, could face a replay of the weekend's travel chaos.
On Saturday, First Great Western apologised after “severe overcrowding” caused delays for Irish fans en route to Cardiff.
Arriva Trains Wales estimates that there will be around 35,000 people wanting to go by rail after tonight's Pool A match.
Customer services director Lynne Milligan said: “We can move on average 10,000 people per hour through our queuing system but unfortunately for some of the busier queues, this could mean up to a three hour wait.”
The company also advised people travelling to Cardiff from Bridgend, Pencoed, Llanharan, Pontyclun and Cwmbran, Pontypool and Abergavenny to catch the earliest trains possible as carriages will already be busy by the time they reach those stations.
Following the weekend's debacle, Welsh Secretary Stephen Crabb urged First Great Western, now rebranded as Great Western Railway, and Arriva Trains Wales to make improvements.
He said: “There is a lot riding on this in terms of Wales’ reputation and Cardiff’s reputation.
“Cardiff has already got a reputation as the best city in Europe in which to watch rugby and we don’t want any transport-related issues undermining the hard-earned reputation that we’re acquiring as a great host city for international events.
“I’ve made no secret of my ambition of wanting Cardiff and Wales to host more of these major international events, whether it’s the UEFA Champion’s League Final or potential bids (for) Commonwealth Games, and having a transport system which is efficient and works effectively at critical moments of peak demand is vital in that.
“So, I was very concerned by the reported experiences of fans on Saturday.”
Mr Crabb argued that World Cup games were very different to Six Nations matches because many people without tickets would still want to come to Cardiff just to soak up the atmosphere.
He added: “We want to show that Wales is open for business and the Rugby World Cup is a fabulous opportunity to showcase Wales and it is passing off very well.
“The atmosphere in Cardiff was just tremendous on Sunday and there are loads and loads of big pluses, but lets fix this.”
Arriva Trains Wales said the usual queuing system will be in place at Cardiff Central station after tonight's game and live updates would be posted online throughout the day.