|This article does not cite any references or sources. (July 2010)|
|North end:||Manchester city centre|
| A6 road
|South end:||M56 motorway junction 3a|
This short section is entirely single-carriageway: it runs in roughly a north-south direction from the junction of the A6 and A62 along Portland Street. It then shares a short section with the A34 (Oxford Street) running west until St Peter's Square. After St Peter's Square, it proceeds south-west along Lower Mosley Street, running past the G-MEX centre (formerly Manchester Central Station), and the Bridgewater Hall. It then turns south along Albion Street and Medlock Street (crossing the Rochdale Canal, the railway viaduct, and the River Medlock), where it meets the A57(M) Mancunian Way at a roundabout.
This section is entirely dual carriageway primary route leading in a southerly direction. The entire section is officially called Princess Road, but many locals refer to it as Princess Parkway (see below). This section predominantly has a 40 mph (64 km/h) speed limit.
This section has many traffic light controlled junctions, including major junctions with the A6010 Manchester middle ring road and A5145 Barlow Moor Road. 0.7 miles (1.1 km) south of its junction with the A5145, the road crosses the River Mersey and meets the M60 motorway at a large free-flow interchange at junction 5.
This section is entirely dual carriageway trunk road, and is an important link between the M60 Manchester Outer Ring road and the M56 motorway. This section is called Princess Parkway and largely has a 50 mph (80 km/h) speed limit. Between the M56 and M60, the road has two intermediate junctions; with the B5166 towards Northenden and Sale Moor, and with the A560 leading to Gatley, Wythenshawe and Baguley. Between junctions, the A5103 here has four lanes in each direction with no hard shoulder. Between the on-and-off sliproads of the junctions, it has 3 lanes in each direction with hard shoulder. At the southern end, the A5103 seamlessly becomes the mainline of the M56 heading towards Manchester Airport, Chester and the M6 motorway. Northbound traffic on the M56 must leave the mainline of the motorway at a sliproad to remain on the M56. Remaining on the mainline leads directly to the A5103.