Cristiano's fine seventh-minute effort proved enough to secure Adelaide United fifth spot in the Club World Cup.
It was a goal deserving of winning the contest, although an obvious lack of skill in the match once again raised question marks over the validity of the competition in its present form.
Egyptian side Al Ahly, the dominant force in Africa over recent seasons, were expecting to reach the semi-finals and even run LDU Quito close in the battle to reach Sunday's decider.
But their lack of a killer punch was exposed and after surrendering a two-goal lead to Pachuca on Sunday they failed to force their way back into this contest too, after falling behind to Cristiano's early strike.
Adelaide held Al Ahly fairly comfortably once Cristiano had put them in front in fine style.
Receiving the ball on Adelaide's left, the Brazilian embarked on a solo burst and fired a superb effort past Amir Abdelhamid.