With the Timberwolves leading 59-57, Garnett and Ricky Davis sparked an 11-1 run late in the third quarter. Garnett scored seven points in the span and Davis had a steal and a dunk to put Minnesota up 70-58 with 25.7 left in the quarter.
Davis finished with 15 points, scoring nine in the third quarter and Troy Hudson finished with 11 points for the (3-2) Timberwolves.
Andre Barrett hit a 3-pointer for Chicago and Martynas Andriukevicius made a baseline jumper to cut Minnesota's lead to 83-81 with 28 seconds left, but Minnesota rookie Randy Foye hit two free throws with 1.3 remaining to secure the victory.
Kirk Hinrich led Chicago (4-1) with 18 points in 29 minutes.
Bulls rookie Tyrus Thomas, who has been impressive throughout the preseason, went by Garnett for a dunk at end of the third quarter. Thomas, the fourth overall draft pick out of LSU, scored 10 points in 19 minutes. He fouled out with 8:16 left in the game.
Ben Gordon was 0-for-7 shooting for Chicago in the first quarter and was 2-for-12 in the game scoring five points.
The Bulls, playing their second game in as many days, trailed 46-40 at the half. Hinrich scored 14 points on 5-of-8 shooting in the first half.
Chicago forward Luol Deng missed his second consecutive preseason game because his travel plans were delayed. He traveled to London to receive his British citizenship. Deng is expected to be back with the club on Saturday. Andres Nocioni started in Deng's place and scored seven points in 19 minutes.