Lacey scored 21 points and the Wolfpack shot 55 percent to beat Duke 87-75 on Sunday, knocking off one of the last three undefeated teams in the country.
The Wolfpack (12-5, 3-1 Atlantic Coast Conference) ran constant double teams at preseason All-American Jahlil Okafor to slow Duke's big man. N.C. State went 10 for 16 from 3-point range to take control, knocking down tough shots and attacking the paint. The Wolfpack stayed aggressive as Duke's defense couldn't get a stop and looked lost.
Okafor finished with 23 points and 12 rebounds, but the Blue Devils (14-1, 2-1) shot 37 percent and just couldn't keep up when N.C. State's offense got rolling.
The Wolfpack ran off seven straight scoring possessions to build a 19-point lead -- Duke's biggest deficit all season by far -- then did enough to turn away the Blue Devils' late comeback attempts.
N.C. State led 37-33 at the break then used the big second-half flurry to push the lead to 72-53 when Lacey hit a straightaway 3-pointer over Okafor with the shot clock winding down at the 5:43 mark.
The Blue Devils made a late push and got as close as seven on Matt Jones' 3 with 1:37 left. But the Wolfpack hit enough free throws down the stretch and got two breakaway dunks from Des Lee in the final minute to punctuate a win that ended with another court-storming celebration for the rowdy home fans.
Ralston Turner scored 11 of his 16 points after halftime, including two straight 3s to break open a tie game. And BeeJay Anya added a career-high 14 points, giving the Wolfpack some of the inside production coach Mark Gottfried has been looking for all season.
N.C. State also blocked 10 shots, four apiece coming from Anya and Kyle Washington.
Quinn Cook scored 18 points for Duke, which missed 20 of 27 3-point tries and couldn't make it through a pair of instate ACC road games unscathed this week. The Blue Devils had a tougher-than-expected win at Wake Forest on Wednesday.
With Duke's loss, No. 1 Kentucky and No. 3 Virginia are the nation's last two unbeatens.
Duke: The Blue Devils tweaked their starting lineup for the first time, going with Jones instead of Amile Jefferson. ... Duke has lost four of five in this building, falling to N.C. State here in 2010 and 2013 then losing to Mercer in its NCAA tournament opener last year. ... Duke had never trailed at the half or by six in any game before Sunday.
N.C. State: This marked the first time since 1992 that N.C. State played consecutive games against top-five opponents. The Wolfpack lost at No. 3 Virginia on Wednesday. ... N.C. State shot 58 percent after halftime.