Chile is now topping Group B of the tournament with four points and a goal differential of two.
The landmark arrived in his 150th game, with a superb Kerem Demirbay opener and Timo Werner's brace sealing a 3-1 win over 10-man Cameroon at the Confederations Cup.
But their hopes of a comeback were effectively extinguished when Mabouka was eventually dismissed for a risky challenge on Can, referee Wilmar Roldan first booking Siani and then producing a red card for the midfielder before reviewing the footage a second time on the protests of Cameroon players.
Werner then gave Germany a two-goal cushion with a diving header, his first goal at senior global level, from Joshua Kimmich's cross on the right wing.
The Gunners' star, voted man of the match, became Chile's all-time top-scorer with his 38th worldwide goal after capitalising on an early mistake in the German defence.
"They (Chile) are a world class team, a fantastic team, and have played some of the best teams in the world off the park".
Arsenal's Alexis Sanchez became Chile's all-time top-scorer with his 38th worldwide goal in Thursday's 1-1 draw with Germany at the Confederations Cup. However, the Chileans came within inches of scoring the game's second goal in the first half. The Indomitable Lions have had a tough time of things in Russian Federation thus far, losing their opening match 0-2 to Chile before drawing 1-1 with Australia on Thursday evening. No other team in this tournament would want to face Cameroon one on one.
Stindl's outstanding ability operating between midfield and attack for Gladbach last season helped the former Karlsruher and Hannover player to produce a phenomenal 18 goals, 11 of which were registered in the Bundesliga.
But Postecoglou believes the scenario of having to win plays nicely into his players' hands. "We weren't at the World Cup", he said.
"But we recovered immediately and our goal was excellent, it was a model goal scored from a couple of passes".
Had Germany boss Loew made a decision to bring his full strength team to Russian Federation, it is unlikely Stindl would be here.
Alexis Sanchez went tumbling to ground early on following a last-ditch intervention from Mark Milligan, but the video assistant referee dismissed penalty claims as replays showed a clear touch from the Australian defender.
Chile's coach Juan Antonio Pizzi has hinted goalkeeper Claudio Bravo could play for the first time since picking up a calf injury playing for Manchester City in April.