The fan, who was thrown out of the match between Australia and India, was reported to have filed an assault charge following the incident.
While the World Cup's organiser, the International Cricket Council (ICC), attempted to defuse the row by saying the fan's removal was for drinking from a can, which is a prohibited item, the PR backlash has caused Pepsi considerable embarrassment.
Pepsi said in a statement to Marketing this week: "Establishing and enforcing rules (either in the stands or on the playing field) rests with the event organisers. Pepsi is solely focused on supplying our products to spectators."
The incident is the latest in a line of Pepsi-Coke conflicts to surface at sporting events. At last year's FIFA World Cup in Korea and Japan, spectators were prevented from taking Pepsi into the stadia, as Coke was an official partner.
The rivals also clashed over their use of David Beckham in World Cup marketing campaigns, following Coke's use of the England captain on promotional packaging. Pepsi has an individual tie-up with Beckham.
At the Cricket World Cup, the ICC has already attacked Samsung over alleged ambush marketing activity, predominantly in India. LG Electronics is the tournament's other official global partner.
England's team sponsor, Vodafone, only secured its appearance on the team's shirts at the last moment following a separate regional deal with the ICC's commercial arm, IDI (Marketing, February 6)
COMMENT
The latest ambush marketing incident underlines the dangers of rights-holders taking an over-zealous approach to protecting the exclusivity of official sponsors.
Although the World Cup organiser is claiming it is the can rather than the brand that led to the fan's ejection, there is little doubt that heavy-handed tactics can trigger major PR backlashes against sponsors.
Pepsi will be hoping that this is not the case in South Africa.