Australia is back in the running for the first place in the round of 16 of a World Cup in 16 years, and Tunisia is once again threatened with the traditional elimination of the preliminary round.
The Socceroos defeated the North Africans 1-0 (1-0) on Saturday and have three points going into the final day of Group D.
Tunisia have only one point and also meet defending champions France.
Mitchell Duke (23rd minute) scored for the Australians in front of 41,823 spectators at Al-Dschanub Stadium.
Despite numerous interruptions due to minor fouls, German referee Daniel Siebert had no problems directing the intense game at his World Cup debut.
"That was a strong performance by the whole team of referees," said Hamburg Bundesliga referee and MagentaTV expert Patrick Ittrich.
Both coaches only changed their starting formations in one position compared to the first matchday.
Fran Karacic replaced the injured Nathaniel Atkinson at right-back for Australia, who only reached the round of 16 at a World Cup in Germany in 2006.
In midfield, coach Graham Arnold once again relied on Jackson Irvine from second division club FC St. Pauli and former Bundesliga professional Mathew Leckie.
For the Tunisians, who have never progressed beyond the group stage in their previous five World Cup appearances, Naim Sliti has attacked in place of Anis Slimane.
Australia's coach Arnold had expected an "extremely physical game" - and he was right.
There was a lot of fighting but little creativity to be seen.
The Socceroos, however, showed a clear improvement overall after the 4-1 swatter against France and set the tone in the first half.
They were rarely really dangerous.
After a good 20 minutes, striker Duke rewarded their efforts with the 1-0.
The 31-year-old initiated the attack himself and then headed Craig Goodwin's slightly deflected cross into the right corner.
The Tunisians also found it difficult to create really compelling chances.
When they came forward, midfielder Ellyes Skhiri from 1. FC Köln was usually involved.
A shot by Freiburg native Mohamed Dräger was blocked by Australia's defender Harry Souttar in dire straits (41').
Only a short time later, the overall very conspicuous captain Youssef Msakni missed the best opportunity to equalize, which by now would no longer have been undeserved.
In their 18th World Cup game, the Australians went into the break for the first time with a lead.
In the second half, the Tunisians increased the offensive pressure, but they still lacked precision.
The Australians, known for their passionate style of play, resisted.
20 minutes before the end, Leckie even slipped past the 2-0.