Diggins scored 17 of her 22 points in the first half to lead No. 5 Notre Dame to an 87-57 victory over Kansas State on Thursday night in the World Vision Classic.
Diggins scored 15 of the Fighting Irish's first 23 points, leading them to a 23-10 lead 8:20 into the game.
"She is a very, very tough player to defend," Kansas State coach Deb Patterson said of Diggins. "As a young and inexperienced team, it's a great challenge. Once she gets in rhythm and measures you as a defender, it becomes a little bit of a cat and mouse game. And you can be in the position of being the mouse in a hurry. She is one competitive kid."
Natalie Achonwa added 13 points, Kayla McBride had 12, and Kaila Turner and Ariel Braker chipped in 11 apiece for Notre Dame (8-1), which led 49-25 at halftime.
"We wanted to come out and have a good start from the beginning," Diggins said. "We played similar teams to Kansas State like Central Michigan and Utah State and had trouble containing the ball and the (defensive) rotation. We're a young team and we have our struggles, but we've been improving at that."
Brittany Chambers had 18 points and seven rebounds, Haley Texada scored 11 points and Ashia Woods added 10 for the Wildcats (7-3).
Chambers, who averages 19 points, scored only five after halftime.
"I think we shut down Chambers in the first half," McGraw said. "She got a lot of points late."
Diggins, who had 17 points on 6-for-9 shooting at halftime, also led Notre Dame with four assists in the first half. McBride had 10 points at the break for the Irish, who shot 55 percent (16 for 29) in the opening half.
Reserve Haley Texada led the Wildcats with eight points in the first half.
Notre Dame will face No. 22 Texas A&M on Friday for the tournament championship after the Aggies beat Old Dominion 78-55.