STANFORD, Calif.- Backed by a hat trick from Carolin Troncelliti, No. 20 Northwestern upended No. 11 Stanford 4-1 on Wednesday afternoon at the Varsity Turf in a battle of nationally-ranked teams.

Wednesday's game against Northwestern was the second in a series of top-25 opponents featured on Stanford's schedule, with matchups against Iowa, North Carolina, Syracuse and Connecticut still to come.

Three days after pushing No. 1 Maryland to the limit in a 3-2 double-overtime loss, Stanford was unable to generate anything offensively from the opening draw.

Northwestern took a 2-0 lead into halftime, with Troncelliti putting away her first goal of the afternoon just seven minutes into the contest before Tara Puffenberger added an unassisted score in the 29th minute.

Stanford, which surged ahead after trailing at halftime on Sunday against Maryland, went into the break looking for a second-half spark. The Cardinal received a boost at the 41:52 mark, when Alex McCawley scored her third goal of the year to slice the deficit to 2-1. Sharing the team lead in goals with Hope Burke, McCawley fired a rocket into the cage from just inside the circle.

However, the Wildcats countered quickly afterward, with Troncelliti scoring her second goal of the game following a nice cross from Catherine Franklin.

Eight minute later, Troncelliti found the cage again, this time after taking a pass from Puffenberger and slipping a shot past Dulcie Davies.

Shots were even at 11 apiece while Stanford owned a 7-3 advantage in penalty corners.

Becky Dru led the Cardinal with three shots, all following penalty corner opportunities, while Hope Burke added two.