"The biggest improvement for me since the ODI's has been the clear plans and execution from the bowlers," Du Plessis said.
The Proteas hold an unassailable 2-0 lead in the three-match T20 International series and are aiming to finish off the challenging tour on a positive on Tuesday.
"We were down and out after we were outplayed in the ODIs," Du Plessis said.
"To come back like this shows huge character and heart, I'm proud of the way the guys have performed in this series so far. Our death bowling in the last two games has been brilliant and we have been effective upfront as well. I'm pleased with the contributions from the bowlers at the moment."
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"There is an option to try out some new combinations in the next match, especially considering that we are eight games away from the World Cup," Du Plessis said.
"We know what the current combinations are capable of, so the series win has given us some space to try out one or two tweaks. The main objective will be to try and give the players who haven't had any game time an opportunity," he added.
Conceding that the Proteas were not "firing at our potential", Du Plessis said there was always room for improvement.