2021 FSA Federation Cup

The 2021 Football South Australia Federation Cup, also known as the 2021 FFA Cup South Australian preliminary rounds until the semi-finals, was the 108th running of the Federation Cup, the main soccer knockout cup competition in South Australia. The competition also functioned as part of the 2021 FFA Cup preliminary rounds, with the two finalists qualifying for the main knockout competition.

Adelaide Olympic were champions for the second time, defeating Adelaide City 2–1 in the final, defending their 2019 title.

Teams
A total of 52 teams participated in the competition, 49 from the Greater Adelaide area, two from the Adelaide Hills region and one from Gawler and Port Pirie. National Premier Leagues South Australia, State League One and State League Two represent levels 2–4 on the unofficial Australian league system and are required to participate in the Federation Cup. The South Australian Regional Leagues represent level 5. The South Australian Amateur Soccer League is not represented on the national league system. Adelaide United Youth are not eligibile for the tournament, as the senior team entered the FFA Cup competition at the Round of 32.

First round
The first round of the Federation Cup was also the third round of the 2021 FFA Cup preliminary rounds. Fulham United (3) received a bye to the second round.

Times before 4 April are in ACDT, times on or after 4 April are in ACST

Second round
The second round of the Federation Cup was also the fourth round of the 2021 FFA Cup preliminary rounds, featuring 21 teams from the previous round and the 11 teams from the National Premier Leagues South Australia.

All times are in ACST

Third round
The third round of the Federation Cup was also the fifth round of the 2021 FFA Cup preliminary rounds.

All times are in ACST

Quarter-finals
The quarter-finals of the Federation Cup was also the sixth round of the 2021 FFA Cup preliminary rounds.

All times are in ACST

Semi-finals
The semi-finals of the Federation Cup was also the seventh round of the 2021 FFA Cup preliminary rounds, with the two winners qualifying for the 2021 FFA Cup.

All times are in ACST