Defending champions Argentina and five-time world champions Brazil remained on course for a semi-final showdown in the men's football competition at the Beijing Olympics on Wednesday.
Current world champions Italy emerged as the best of the rest and were rewarded with the kindest draw with the prospect of a semi-final against Nigeria if the Group winners also win their opening play-off match.
Argentina kept Barcelona star Lionel Messi on the bench but were still too good for Serbia for their ninth successive Games win, an Olympic record after going through unbeaten in Athens four years ago, when the South American won the gold medal.
The albieceleste beat the Serbs 2-0 thanks to a penalty by Ezequiel Lavezzi in the 12th minute and a free kick from Angel de Maria more than an hour later.
Chelsea striker Salomon Kalou gave Ivory Coast a 1-0 win over Australia to qualify second in Group A and an African showdown with Nigeria in the quarter-finals.
Argentina play the Netherlands in the quarter-finals while Brazil play Cameroon.
The quarter-final matches will be played on Saturday.
A brace from Thiago Neves helped Brazil to beat hosts China 3-0.
Belgium beat New Zealand 1-0 to be the second qualifiers from group C and a date with Italy.
The Italians and Cameroon both progressed to the quarter-finals after fighting out a goalless draw in Group D which saw the African side play with 10 men for all but 32 minutes.
Cameroon, the 2000 Olympic champions, will be missing the red carded Georges Mandjeck and defender Paul Bebey when they play Brazil.
Nigeria finished top of Group B when they beat the United States 2-1 with the Netherlands leapfrogging the USA to be the second qualifiers when a late Gerald Sibon penalty secured a 1-0 win over Japan.
