From August 8 the current 17.22 from Edinburgh Waverley to Motherwell is being extended to Glasgow Central, but will follow an alternate route so will no longer call at Motherwell.
However, it will now stop at Uddingston and Bellshill.
Passengers are encouraged to get the 17.39 from Edinburgh which arrives at Motherwell at 18.34, one minute earlier than the 17.22 does at the moment.
A ScotRail Alliance spokeswoman said: “Extending the 17.22 train will help us to best meet the growing customer demand between the two cities.
“We recommend Motherwell customers who normally get this train should go for the faster 17:39 service which calls at Motherwell at 18:34.
“We’re also encouraging all customers to check their journeys online or via the ScotRail app, selecting a date from August 8.”