Organisers, concerned at a negative image caused by empty stands at matches not involving the home team, have been handing out tickets to encourage better attendance but with little success.
They will try again on Sunday when Ghana and Tunisia meet in Franceville in the last of the quarter-finals.
"We are giving away free tickets to students and workers and also free transport," said the home organising committee's spokesman Louis-Claude Mouzieoud
The other match in Libreville between the home team and Mali is over-subscribed. Gabon hosts two quarter-finals on Sunday, with Saturday's two games in Equatorial Guinea which is co-hosting the tournament.
Attendance has long been a Nations Cup problem. Few travelling fans attend, mostly government sponsored, but never enough to replicate the carnival-like atmosphere that hordes of Danish, Dutch or Irish fans have brought to past European Championships and World Cups.
Travel costs in Africa are exorbitant and accommodation and other facilities minimal.
The fans who do attend show little enthusiasm for matches involving anyone but their home team. Gabon and Equatorial Guinea have played to packed stadiums but other games have attracted few spectators.
On Tuesday, while Gabon were beating Tunisia before a capacity crowd in their final group game in Franceville, organisers granted free entry to the other Group C match being played at the same time, between Morocco and Niger in Libreville.
Those who bothered to turn up to Libreville's new, 45,000-capacity stadium quickly installed themselves in seats around the press box where banks of television sets were showing the Gabon match live. The loudest roar came not from any of the action in the Morocco-Niger encounter but when Gabon scored their winner some 500km away.
If organisers find their offer does not work again in Franceville at the weekend, they might always try the military.
In 1994, hosts Tunisia were dumped out in the first round, causing mass disinterest in the rest of the tournament.
So when Nigeria beat Zambia in the final, a capacity audience was provided by thousands of uniformed conscripts, their brown fatigues and generally silent demeanour ensuring an eerie atmosphere.
Egypt also used shaven-headed young soldiers to fill parts of its empty stadiums when it hosted the finals in 2006.
