On moving day in Gams, neither Lampert nor MacLaren remained flawless, but they were able to establish themselves at the top of the leaderboard thanks to their matching 70's.
"I tried not to think about the score, but to do my thing like I did on the first day," explained MacLaren, about her recipe for success.
Russia's Nina Pegova (70), Marta Silva (70) of Spain, Swede Jenny Haglund (71) and Linda Henriksson (68) of Finland, are two shots behind MacLaren. Henriksson needed 68 shots for her second round - the best score of the day. Englishwoman Cloe Frankish also recorded a 68, which moved her up to 7th place and in a tie with Italy's Stefania Avanzo (70), Valdis Thora Jonsdottir (71) of Iceland and joint overnight leader, Joana de Sa Pireira from Portugal.
Karolin Lampert will have a strong voice on Sunday in the battle for victory, and her bid to become the second German winner in the event's four-year history, after Olivia Cowan's triumph in 2015 but the in-form MacLaren will be hard to beat.
Forty-five professionals and seven amateurs made the cut, which fell at +3, 147.