With five changes from the side which won 4-1 on Wednesday afternoon it was not surprising that Britain took a little time to settle, but it was Sixsmith and her England colleague Tina Cullen who won Britain's second penalty corner in the 23rd minute.
That enabled Denise Marston-Smith to score a soft opening goal which reached the target thanks to a deflection off the American captain, Taccey Fuchs.
Then, after a series of missed chances, Cullen was on hand to finish off a good move between Jane Smith and Mandy Nicholson for Britain's second on the interval.
With Sixsmith and Cullen continuing to buzz and chances being squandered, the game deteriorated until in a late rally Britain scored twice.
The first of them came when Rhona Simpson followed up at a penalty corner, and then a glorious cross-field pass from Sixsmith found Marston-Smith gliding into the circle from the left wing to drive home an unstoppable shot for her second of the game.
Britain's coach, Jon Royce, who had been so critical of his team after the opening game, admitted he was pleased with their first-half performance. "We moved the ball around and took control," he said. "Sadly we took our foot off the gas a bit after the interval."
The teams meet on Monday afternoon for the third and final Test.
GREAT BRITAIN: C Reid (England); J Jack (Scotland), F Greenham, M Clewlow, K Johnson; J Smith, M Nicholson (Capt), D Marston-Smith; J Sixsmith, (all England), R Simpson (Scotland), T Cullen (England). Substitutes used: K Bowden, S Chandler, H Richardson, L Wright, H Rose (all England).
UNITED STATES: L Cellucci; J Reeve, K Kauffman; T Fuchs (capt), C Summer, K James; A Lucas, M Smith, N Pelligren; C Werley, C Tagliente. Substitutes used: J Withrow, M Vizzuso, C DeBow, T Larson, J Toepel.
Umpires: J Duncan (Scotland) and M Brainard (US).Reuse content