The left-arm spinner claimed a hat-trick and became only the second Aussie player to do so after Brett Lee.
Agar is highly inspired by Indian star all-rounder Ravindra Jadeja and wants to be like him.
He praised the Indian cricketer and said the latter inspired him.
I want to play cricket like he [Jadeja] does: Agar
Agar revealed that Jadeja went on to inspire him during Australia's ODI tour of India last month.
"I had a wonderful chat with Ravindra Jadeja after the India series," ESPNcricinfo quoted Agar as saying after the match on Friday.
"He's my favorite player in the world -- I want to play cricket like he does."
He's an absolute rockstar: Agar on Jadeja
Agar lauded Jadeja for his attitude.
"He's an absolute rockstar: smacks them, gun fielder, and spins the ball. But it's just his presence when he's out there, watching his confidence... Just talking to him about spin bowling, keep trying to spin the ball. When he's batting he has a really positive attitude, and he takes that attitude into the field as well," he added.
Agar claims best bowling figures for Australia in T20Is
Agar was exceptional against the Proteas and claimed figures of 5/24.
This is now the best bowling figures for an Australian bowler in the shortest format.
The previous best bowling figures by an Aussie international was James Faulkner (5/27).
Agar also hit a 9-ball unbeaten 20 during Australia's innings.
Jadeja has set the benchmark for rising all-rounders
Agar is a rising all-rounder and has the attributes to shine and be the influential figure. The benchmark set by Jadeja is something not only Agar but several other spin all-rounders will look up to. They will want to execute what Jadeja offers consistently.
How did the first T20I pan out?
Australia lost David Warner (4) early on. Aaron Finch (42) and Steve Smith (45) added 80 runs for the second wicket.
Matthew Wade (18) and Mitchell Marsh (19) made small contributions.
Alex Carey (27) and Agar made the difference to see Australia post 196/6.
In reply, the Aussie spinners claimed seven wickets between them.