The Denver forward was 7 of 11 from long range and finished with a career-high 39 points as the Nuggets handed the Mavericks their fifth straight loss, 106-85, on Friday night.
"He was one of the best players in the game," Gallinari, a 6-foot-10 forward from Italy, said of the 7-foot Nowitzki from Germany. "So you always try to follow and learn from the best. I've watched a lot of videos from him."
Nowitzki, who missed the first 27 games after surgery late in the preseason, had five points in 17 minutes in his third game back. He made two of his first four shots after entering the game to a loud ovation midway through the first quarter. But he missed his last six shots and didn't play in the fourth quarter a night after an overtime loss at Oklahoma City.
"I was a step slow," Nowitzki said. "That was obvious. I had no lift in my jumper. Everything was in and out. That last little thing is still missing. Really, these are my first games in a long time. So it's ugly. I've got to keep fighting, keep working hard in practice days and eventually I'll be able to come back."
O.J. Mayo led Dallas with 15 points but was just 1 of 6 on 3-pointers. The Mavericks shot 38 percent and made just 5 of 25 from long range.
With the Nuggets up 50-47, Gallinari scored five points in the final 5 seconds of the first half, hitting a 3-pointer and scoring on a tip-in just before the buzzer after Denver knocked away a long inbound pass.
Gallinari, whose previous career high was 37 against the New York Knicks last January, opened the second half with a 3-pointer to put Denver up by 11, and Andre Iguodala followed with four from long range in the third quarter, including one after the Mavericks had pulled within five. Gallinari and Iguodala scored all 12 of Denver's points during a stretch that ended with the Nuggets up by 14 late in the third.
Iguodala finished with 20 and was 4-of-6 shooting from long range. Denver made 12 of 28 from behind the arc.
"When we make shots, I think we're pretty good," Denver coach George Karl said. "Iguodala made a couple of shots right at the end of the shot clock that were heartbreakers for them."
Nowitzki made a surprise return at San Antonio on Sunday and played 20 minutes, as planned. He was up to nearly 26 1/2 after playing briefly in overtime of a 111-105 loss to the Thunder on Thursday night. He missed his first two shots against the Nuggets, including his signature one-legged fadeway, before making a 3-pointer and a 19-footer.
A few of Nowitzki's six misses the rest of the night rattled in and out.
"It was too much tonight," Dallas coach Rick Carlisle said. "It was back-to-back games and he isn't limping or anything, but he just can't give us what everyone expects him to give."
Kenneth Faried outrebounded the Mavericks by himself in the first quarter and finished with 19 rebounds and 11 points, his seventh double-double in the past 10 games. The Nuggets had 60 rebounds to 43 for Dallas, and outscored the Mavericks 19-6 in second-chance points in the first three quarters.
"It's a problem that isn't going to go away by talking about it," Carlisle said. "I know we can do it."
Mayo was a little better after a four-game slump punctuated by matching his season low with four points and missing two of three free throws with a chance to tie the score in the loss to Oklahoma City. But he had just two points and took just four shots in the second half.
Gallinari capped a 15-2 run in the first quarter with a 3-pointer and two free throws to give the Nuggets a 21-8 lead. The Mavericks, who fell to 3-10 against teams with winning records, answered with a 10-0 run in the second quarter and got as close as 40-38 on a 3-pointer by Vince Carter.
The Mavericks were given a technical foul when Carlisle called a timeout with 3:02 remaining when he didn't have any timeouts left. ... Mavericks G Darren Collison fell three points shy of his career high with 32 in Thursday's 111-105 overtime loss at Oklahoma City. He had his career high at Dallas in February 2010. ... The Nuggets had double-digit 3-pointers for the second straight game after going the first 29 without one. They were 8-0 last year when they had 10 or more 3s. ... Nuggets G Ty Lawson had 14 assists and no turnovers against the Lakers, the first Denver player to do that since Nick Van Exel against the Mavericks almost 11 years ago.