Dubai - Fit-again South African captain Graeme Smith won the toss and decided to bat in the fourth day-night international match on Friday.
South Africa, who lead the five-match series 2-1, were lucky to have Smith back after he recovered from a hand injury which forced him to miss the last two matches.
They were also boosted by the return of frontline paceman Dale Steyn who missed both the Twenty20 and the first three one-day matches because of a head injury sustained last month.
Paceman Wayne Parnell also returns to the team as Albie Morkel, Lonwabo Tsotsobe and Rusty Theron were left out.
Pakistan left out off-spinner Saeed Ajmal and brought in left-arm slow bowler Abdul Rehman as the only change in the side from the last match.
South Africa won the first match by eight wickets before Pakistan levelled the series with a narrow one-wicket win in the second -- both matches played in Abu Dhabi last week.
South Africa won the third match by two runs in Dubai on Tuesday.
The five-match one-day series will be followed by two Tests.
Shahid Afridi (captain), Mohammad Hafeez, Imran Farhat, Fawad Alam, Younis Khan, Asad Shafiq, Abdul Razzaq, Zulqarnain Haider, Wahab Riaz, Abdul Rehman, Shoaib Akhtar
Graeme Smith (captain), Hashim Amla, AB de Villiers, JP Duminy, Jacques Kallis, Colin Ingram, David Miller, Johan Botha, Dale Steyn, Morne Morkel, Wayne Parnell
Umpires: Zameer Haider (PAK) and Daryl Harper (AUS)
Tv Umpire: Ahsan Raza (PAK)
Match Referee: Andrew Pycroft (ZIM)