"He pushes both buttons, good and bad," Karl said. "There are times when you are happy with him when you walk out of the arena and other times you would like to strangle him."
Smith scored a career-high 36 points, including five 3-pointers, and the Nuggets beat the struggling Chicago Bulls 113-109.
"There are times that he does what we want," Karl said. "Other times he seems like he's asleep."
Carmelo Anthony added 29 points but missed two free throws in the closing seconds, ending his streak of 30-point games at six. That left him tied for the franchise record with Alex English, who did it during the 1982-83 season.
"It would be really special to break a record held by someone like Alex English," Anthony said. "I might still get it this year."
Smith picked up the slack down the stretch, scoring five points in the final three minutes against the team that traded him to Denver during the offseason.
"J.R. gets the game ball tonight," Anthony said. "He took my 30 tonight."
Anthony had 23 points at the start of the fourth quarter, but didn't add to his total until his two free throws with 6:58 remaining gave the Nuggets an 88-87 lead.
Chicago trailed only 99-95 with 3:08 to go before Smith hit a 3-pointer, then followed a steal by Andre Miller with a powerful dunk to make it 106-95 with 2:29 left. Anthony closed out the Bulls with two free throws.
"All week long I practiced to prepare for this game," said Smith, whose clenched right fist went higher and higher with each basket. "Then to win the game was enough for me.
"I just got hot. Once I hit the 3-pointer that beat the buzzer at the end of the third quarter, I felt like I could hit everything."
Hinrich scored seven points early in the second half, helping Chicago build a 70-58 lead. The Nuggets charged back and Smith connected on two 3-pointers, including 33-foot shot at the buzzer, that put Denver up 79-78 after three quarters.
"We lost Smith in more than just the third quarter," Chicago coach Scott Skiles said. "We had a hard time with him pretty much the whole game."
Miller's spinning layup in the final 23 seconds tied the game at 55 at the half. Deng had 14 points in the second quarter, capitalizing on the extended absence due to foul trouble of Anthony, who had only one point in seven minutes in the period.
Anthony missed badly on his first two attempts from outside before softly converting a reverse layup midway through the first quarter. He finished with 15 for the period and Denver had a 31-24 lead.
- Adrian Griffin was inactive for Chicago with a strained right calf. C Ben Wallace had his first double-double of the year.
- G Earl Boykins missed the game with a stomach virus.
- G Miller played in his 295th consecutive game.