Work on £100,000 of changes to £21m Postwick Hub junction is to be brought forward by a day - to avoid disrupting football traffic heading home from Norwich City's Championship fixture at the weekend.
The overnight installation of protective barriers, to pave the way for the construction of a segregated left turn lane on the junction's north-west roundabout, had been scheduled to take place on Saturday night.
But with the Canaries' Carrow Road game against Sheffield Wednesday switched to a 5.30pm kick-off so it can be screened on television, Norfolk County Council bosses have decided to put in the barriers on Friday night instead.
From 8pm on Friday the segment of the roundabout to be widened will be closed while the barriers are installed.
That will mainly affect traffic from the east leaving the A47 and heading towards Thorpe St Andrew on the Yarmouth Road and onwards to destinations including Norwich International Airport.
Those vehicles will be diverted via the westbound A47 and the A146 Trowse Bypass.
Traffic heading in the other direction - leaving Thorpe St Andrew via Yarmouth Road to join the eastbound A47 will not be significantly affected, council bosses say.
Traffic from the east, heading north from the Postwick junction towards Green Lane, will be able to use the new bridge and access roads to reach the Peachman Way roundabout.
A spokesman for Norfolk County Council said: 'Installation of the barriers is expected to take several hours and the partial closure of the roundabout will be lifted as soon as it is safe to do so, but no later than 6am on Saturday.
'This arm of the roundabout will then be reduced to a single lane. This is a change to the original proposals to provide more working space and reduce the overall construction period.
'The new segregated left turn lane is designed to improve the flow of traffic through Postwick Junction during the morning peak, when delays in clearing through the north-west roundabout resulted in queues that occasionally tailed back through the traffic lights and the Oaks Lane roundabout.'
The council is aiming to complete the work on the new lane within the school holiday, so the segregated left turn is available on September 5.
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