Cape Town - JP Duminy bowled two overs in Wednesday night's 6-wicket loss to Australia at Newlands and went for 18 runs.
It was his best performance in a while.
The sixth bowler remains one area of concern for the Proteas as they head into the ICC World Twenty20 in India this month, and Duminy is almost certain to be backed with that responsibility.
Having carved a reputation for himself as a partnership-breaker over the course of his career, Duminy looks to have lost his rhythm in recent months.
But the signs were there for Du Plessis on Wednesday that South Africa's all-time leading T20I run-scorer was turning the corner with the ball.
"The sixth bowler is really important to me and I do feel that we’re at our best when we have that sixth bowler option," Du Plessis said in his final press conference before departing for India.
"That’s why I was trying to get JP to bowl as much as possible when the situation allowed for it … he’s so important as that sixth bowler.
"I thought he bowled really well tonight. It looked like he had good control and some dip on the ball.
"He’s vital ... hopefully tonight (Wednesday) is the start of the turn-around and some really good bowling from JP."
The Proteas have two specialist spin bowlers in their squad - Imran Tahir and Aaron Phangiso.
Phangiso was only given the green light to take part in the tournament on Tuesday after a series of ICC-conducted tests cleared his bowling action.