Saracens 24 - 23 South Africa
Attendance: 46,281
The Springbok's suffered their third straight defeat on their tour of Europe as Premiership leaders Saracens came from 18-6 behind to win at Wembley.
Saracens, whose team included nine South Africans came back in the second half with tries from Ernst Joubert and Brad Barritt and former Springbok fly-half Derrick Hougaard kicked 14 points to beat the World Champions.
"This victory is massively up there with previous great Saracens performances," said Saracens lock Hugh Vyvyan.
South Africa play Italy on Saturday before finishing their tour against Six Nations Grand Slam Champions Ireland on 28 November.
The game attracted a crowd of 46,281 to Wembley.
Saracens:
Horak; Cato, Ratuvou, Barritt, Tagicakibau; Hougaard, de Kock; Gill, Reynecke, Skuse, Botha, Vyvyan, van Heerden, Melck, Joubert.
Replacements: Nieto for Horak (49), Penney for Cato (40), Barrett for de Kock (38), Brits for Reynecke (40), Goode for Skuse (49), Saull for Melck (47).
South Africa:
Rose; Ndungane, de Jongh, Olivier, Nokwe; Pienaar, Adams; van der Merwe, Strauss, van der Linde, Hargreaves, Bekker, Deysel, Potgieter, Johnson.
Replacements: Viljoen for Olivier (68), Bosman for Pienaar (68), Hougaard for Adams (40), Maku for Strauss (68), W. du Preez for van der Linde (10), Rossouw for Bekker (40), Raubenheimer for Johnson (68).
Ref: James Jones (WRFU).