Northern rail cancellations are expected on Christmas Eve with the franchise blaming "unprecedented" sickness levels and drivers on leave.
A spokesman said services would be affected in Lancashire, Liverpool and Manchester and advised people to check online before travelling.
The warning comes after commuters were hit by delays and cancellations when new winter timetables were launched.
"We are sorry for any disruption customers may face," they added.
"Alongside the annual leave entitlements at this time of the year, we currently have unprecedented levels of sickness," the spokesman said.
"That means we expect there to be some pre-planned cancellations on certain lines."
Northern confirmed three services would be affected with a replacement bus service running between Liverpool Lime Street and Wigan North West, a reduced service from Manchester Piccadilly and Hadfield and a combination of both between Lancaster and Morecambe.
Steve Rotheram, Metro Mayor of Liverpool City Region, said there needed to be "some consequence" for the "very, very poor service" and "chaos" rail passengers have faced on the network.
The Department for Transport (DfT) reiterated its position on the future of the rail firm, which has received widespread criticism for regular disruption to services.
A DfT spokesperson said: "As the Secretary of State for Transport, Grant Shapps, announced at the Transport Select Committee in October, we are developing contingency plans for the replacement of the current franchise with either a new short-term management contract with Northern or the Operator of Last Resort."
David Brown, managing director at Northern, said the franchise had faced "unprecedented challenges" outside its control.
He said the late delivery of major infrastructure upgrades, strike action and lower than expected economic growth have had "a significant effect" on the business plan agreed with government in 2015. He said Northern and parent company Arriva "remain fully committed to delivering the transformation of the north's railways and improving customers' experience".
A £600 million investment would see 2,000 extra services per week, better stations and better offers for customers, he said.