The M18 becomes Nelson Mandela Drive southwards, being 4 lanes in each direction, and reaches a major junction north of Fountains Valley (known as Fountains Circle), where it meets the M7 road (George Storrar Drive), the southern terminus of the M5 road (Elandspoort Street) and the northern terminus of the R21 road (which connects to O. R. Tambo International Airport).

[5] The M7 joins the M18 and they become one road south-west named Christina De Wit Avenue.

After a kilometre, the M7 becomes its own road westwards while the M18 remains as Christina De Wit Avenue southwards to enter the city of Centurion.

[6] The M18 continues southwards to cross the N1 highway (Danie Joubert Freeway; Pretoria Eastern Bypass) and pass through the suburb of Irene, where it meets the M31 road (Nellmapius Drive).

It bypasses Thembisa Hospital southwards as Reverend RTJ Namane Drive.