Saturday's format saw the teams playing foursomes, or alternate shot. They will play stroke play on Sunday with each players score counting towards the team total.
Korea's Meena Lee and Bo Bae Song shared the first-round lead with the Swedes, but could only manage an even-par 72 to end three back in second place at minus-7.
Minea Blomqvist and Riikka Hakkarainen of Finland posted their second straight 3-under 69. They were joined in third place at 6-under-par 138 by the Colombian sister team of Christina and Marisa Baena.
The Welsh tandem of Becky Brewerton and Becky Morgan stand alone in fifth place at 4-under-par 140 after back-to-back 70s at Gary Player Country Club. Germany's team of Anja Monke and Miriam Nagl are in sixth at minus-2 after an even-par 72 on Saturday.
The United States pair of Paula Creamer and Natalie Gulbis struggled in the second round. They stumbled to a 3-over 75 to drop into a share of seventh place. They were joined at 1-under-par 143 by Scotland's Catriona Matthew and Janice Moodie, as well as Paula Marti and Marta Prieto of Spain.
The Swedes got off to a good start as they birdied the first. However, a double bogey at the fourth and a bogey at the seventh dropped them to minus-5, four shots behind the Koreans.
'On those first few holes, Liselotte was probably wondering who she was playing with,' joked Sorenstam, who found water off the tee at the fourth.
The Korean duo converted three birdies in their first four holes to move to 10 under. However, they stumbled to a bogey on the fifth to slip back to 9 under.
The par-5 ninth proved to be a key turning point in the round. The Swedes carded an eagle, as Sorenstam knocked her approach to 6 feet and Neumann sank the putt, to jump to minus-7. The Koreans, meanwhile, bogeyed the hole to slide to 8 under.
'We struggled in the beginning,' Neumann said. 'But the turning point came at the ninth and we took advantage of that.'
Each team parred 10 and birdied the 11th as the Koreans held their one-shot lead. The par-3 12th was the next big swing as the Swedes carded a birdie to get to 9 under, while the Koreans tripped to a bogey to fall to back at 8 under.
The Swedes gave a stroke back with a bogey on the 13th, but quickly atoned for that error with a birdie at the next. They moved to 10 under with a birdie on the par-4 17th.
The Koreans parred four straight holes before a bogey at the 17th left them three behind the leaders.