Not after the Wildcats hit 8 of 15 from downtown in last month's win over the Fighting Illini (19-8, 6-7) in Champaign.
Not after they nearly upset Ohio State last week by nailing 11 three-point baskets.
"If you let them get clean looks from 3, a lot of them and they make them, they made 11 the other night out of 26 in Columbus, it's on, now," Groce said.
With that in mind, Illinois smothered Northwestern's long range attack, which entered Sunday night's game ranked third in the Big Ten in 3-pointers made per game. The Wildcats finished 5 of 27 from deep, falling behind by double digits at halftone and losing 62-41.
"When we play well it really starts with our defense," Groce said. "I thought we were really locked in and defended for the duration of the game. Our communication has gotten a lot better. Guys executed the game plan well and I thought we played exceptionally hard."
Facing extreme attrition and down to eight scholarship players in the rotation, the Wildcats (13-13, 4-9) have turned to execution and efficiency on the offensive end.
"It's really hard to guard," Groce said. "They do such a great job. They're so unselfish. They move, they cut as hard an anybody in the country. They screen, they've got great spacing. Obviously they're really well coached."
The Wildcats were never able to get that offensive system rolling. They only managed 15 points in the first half while shooting 5 of 23 (21.7 percent) from the field.
"It didn't seem to have a flow to it," Wildcats Coach Bill Carmody said.
"They guarded us in a similar fashion to what they did in Champaign, switching (on screens), which a lot of teams do. But we didn't handle it very effectively."
"I think we took away a lot of their offensive schemes that they wanted to do," Illinois guard Brandon Paul said. "They want to slow the game down, but we made them speed up because we got out to a lead. They usually want to slow down."
Groce credited his team's communication and unselfishness for the defensive success, saying his players played like a collective five-man unit.
"I think some people when they think unselfishness they immediately think almost exclusively on offense," he said. "But defensively right now we're just in the right position more, we trust one another more, we cover for one another better."
The first meeting between the in-state rivals left the Illini with wounded pride. Northwestern scored 68 points while executing the offense at a high level in the win. Five first half 3s helped build a 36-21 halftime lead that Illinois wasn't able to respond to.
According to guard Tracy Abrams, that performance served as motivation in the rematch.
"They killed us, pretty much," he said. Ain't no more motivation than that. They came out and destroyed us at home.
"They killed us in the beginning of the game in Champaign. We know how important the start is when you play a team like Northwestern. They kind of hold the ball a lot and take advantage of each defensive situation, so we came out and wanted to be aggressive."
Sunday's prime defensive performance was the latest in a string of games in which the Illini have displayed improvement on that end of the floor.
In the last three games, teams have averaged 51 points and shot 26.6 percent (16-of-60) from the 3-point line against Illinois.
Coincidently, all three of those games ended in Illini victory.
"We've got to make shots, and we weren't able to do that," Carmody said. "Their defense gets the credit."