The 37-year-old former Olympic champion took the 100 metres in the Golden Gala at a rainswept Olympic stadium in a time of 10.20sec, 0.03sec faster than he had run in winning at Hengelo on Saturday.
Christie had to stay ahead of the two Nigerians, Deji Aliu and Davidson Ezinwa, who were also credited with 10.20.
The Briton followed up with a 20.67sec 200m, taking fourth place behind Namibia's Olympic silver medallist, Frankie Fredericks, who recorded 20.24.
Sally Gunnell, running her first international 400m hurdles since being carried from the Olympic track in Atlanta, finished fifth behind Morocco's Nezha Bidouane, who overhauled the US world champion, Kim Batten. Gunnell said: "The good thing is I got through the race without any pain whatsoever."