Zanna scored 16 of his 18 points in the opening half and Pitt built a 28-point advantage on the way to a 77-48 rout of Colorado in the second round of the NCAA tournament on Thursday.
The Panthers (26-9), seeded ninth in the South Region, shot 51 percent and played stifling defense in advancing to a third-round matchup Saturday against either No. 1 seed Florida or No. 16 seed Albany.
Colorado (23-12) was eager to make amends for an early exit from the tournament a year ago, but had no answers for the 6-foot-9 Zanna. The Pitt center made six of seven shots in the first half, and the Panthers didn't have any difficulty finishing off the overwhelmed Buffaloes.
Josh Scott led the Buffaloes with 14 points, however Colorado couldn't overcome a subpar performance for Askia Booker, who missed his first seven shots and didn't score from the field until four minutes into the second half.
Cameron Wright had 11 points and Lamar Patterson finished with 10 for Pitt, which moved from the Big East to the Atlantic Coast Conference this season, where it finished fifth.
Zanna, who had a big game in the ACC tournament with 19 points and 21 rebounds in a win over North Carolina, didn't attempt a shot in the second half, when coach Jamie Dixon gave his starters plenty of rest. Michael Young had nine points in 21 minutes and no regular played more than 30.
Colorado, whose 23 wins are the second-most in school history, entered the game coming off one of their worst offensive performances of the season in 20-point loss to Arizona in the Pac-12 tournament. The Buffaloes were limited to a season-low 15 field goals while shooting 29 percent from the field with Scott finishing with a season-low four points and two rebounds.
It didn't get any better against Pitt, which is in the NCAA tournament for the 10th time in 11 seasons under Dixon. The Panthers lost in the second round to Wichita State a year ago and will be looking for their first trip to the round of 16 since 2009 when they try to extend their first season in the ACC on Saturday.
Colorado shot 29.4 percent from the field in the opening half, with Booker missing all four of his attempts from the field and being limited to a pair of free throws. Scott had five points on 2 for 3 shooting, but an even bigger indication of the team's troubles: the Buffaloes had zero assists and 10 turnovers.
Pitt, meanwhile, matched its point total for its previous game, a 51-48 loss to Virginia in the semifinals of last week's ACC tournament. The Panthers had 13 assists on 18 baskets in the first 20 minutes, and they outscored Colorado 12-2 in points off turnovers in building the 28-point halftime lead.
Booker, like Scott averaging 14 points per game, finished with six on 2 for 9 shooting. Xavier Johnson scored 11 for the Buffaloes, who made a 3-pointer at the buzzer to avoid finishing with fewer points than Pitt scored in the opening half alone.
The 29-point defeat was the largest-ever for the Buffaloes in the NCAA tournament. The previous low point was a 73-46 loss to eventual national champion Cincinnati in 1962.