England carved out a 59-53 win over South Africa to secure a Test series victory in Cape Town.
In what was the 60th meeting between the teams, George Fisher proved the difference following her half-time introduction after South Africa largely matched their visitors.
It means Jess Thirlby wins her first series since replacing Tracey Neville as head coach.
"The thing I'm most pleased with is the improved performance," she said.
"It was great, quick learning from last night into tonight. We were tactically a bit smarter.
"I thought the changes had a great impact tonight."
The first Test on Friday had gone to extra time with England eventually winning 63-58 and the second Test started just as tightly, with little separating the sides early on.
But the Roses, ranked third in the world, were able to open up a slender four-goal lead at the end of the first quarter.
The Proteas clawed back in the second quarter with a three-goal run but Thirlby's Roses went into half-time 29-27 up, Kadeen Corbin scoring in the final play of the half.
Fisher was brought on at goal shooter after the break with Ellie Cardwell making way, and once again, South Africa scored three back-to-back goals en route to taking the lead early in the third quarter.
But England edged them out as the error-strewn quarter progressed and led 43-41 at the whistle.
Thirlby made two changes with Fran Williams - who had made way for Razia Quashie in the second quarter - coming back on at goal defence and Natalie Panagarry replacing Laura Malcolm at wing defence, with England going on to control the final quarter, easing out to a six-goal lead.
England's third and final Test against South Africa takes place on Sunday.
"I would like to think I could test some other combinations tomorrow," added Thirlby.
Roses captain Natalie Haythornthwaite added: "We wanted to win back-to-back games, we've got one more to go and we want to seal the deal."
England: GK Francis, GD Williams, WD Malcolm, C Clarke, WA Haythornthwaite, GA Corbin, GS Cardwell