Young suffered an ankle sprain in practice this week and wasn't able to play against the Bruins.
"We thought he'd be back for the game," Auburn coach Jeff Lebo said. "He hurt it the second practice back and he didn't have any swelling in it. He didn't really practice in the last two days and couldn't go in the shoot-around. I guess it's kind of day to day."
With Young on the bench in a warm-up suit, only seven Tigers saw action against the Bruins and four of those played 35 minutes or more.
"I was awfully proud of my team for gutting out a victory with no Ian Young out there and no Ronny LeMelle (knee injury) still," Lebo said. "We played really seven guys of which three came as walk-ons and three are freshmen. Q (Quinnel Brown) is the only guy (not in that category). I thought our kids played hard and competed and we ran out of steam a little bit at the end with our pressure defense.
"Nate was cramping up and Q was having to battle," Lebo added. "We had some foul problems with (freshman guard Daniel) Hayles (and Toney Douglas both with four fouls), but we made it through okay. I thought fatigue was a factor especially in the second half defensively."
Coach Jeff Lebo said he was pleased his short-handed team pulled out its ninth victory in Auburn's final pre-conference game.
The lack of depth and fatigue was more evident on the foul line than defensively as the Tigers sank 14 of 28 foul shots on the night.
"Like I said, fatigue," Brown said. "When you're fatigued a lot of shots are going to fall short."
Watson, who scored all 12 of his points in the second half, made only 2-5 from the line. However, he made the first of two free throws with two seconds remaining to make it a two-possession game at 73-69. He also added seven of Auburn's 15 assists.
Douglas and Howell, who have played some point guard throughout the season for the Tigers, handled duties with Young injured. "It was the same," Douglas said. "I just got a little fatigued like Q and Nate said. In the first half we were standing around and not moving. Our coach told us to pass and cut and stop standing, and we did that in the second half and we executed."
Douglas scored 22 points, but had only one assist and four turnovers. Brown, who hit 7-12 field goals and led all rebounders with 11, scored 19 points for the Tigers in 37 minutes.
Freshman guard Frank Tolbert got his first collegiate start and contributed seven points, two rebounds and an assist.
Walk-on forward Moses Edun filled in for six minutes and was 2-4 from the free throw stripe while adding two steals on the defensive end of the court.
"Moses has been good in practice and he's been accountable and it's been noticeable," Lebo said. "He helped us and made a couple of nice plays. Defensively, against their post guys I thought he was a little more active (than 6-11 freshman Ryan Daniel would have been)."
Brett Howell plays defense vs. the Bruins. The guard was one of two substitutes that Auburn used in the game. The other was walk-on Moses Edun.
The game was back and forth early as Belmont held a 14-13 advantage, but Auburn took over the lead for good with 11:20 left in the first half after a lay-up and three-point basket by Tolbert. The Tigers led by as few as a single point and as many as 10 in the second half.
Auburn finished its regular season non-conference schedule at 9-4 and returns to action on the road at Mississippi State on Wednesday. The next home game for the Tigers is on Jan. 12 against the Florida Gators.
"I think you'll see us play a little differently once we get into conference play because we have to," Lebo said about the Tigers lack of size. "Inside we're going to have to find a way to discourage the ball from going in there, but a lot of times when you do that it's going to open up the perimeter."
Auburn out-rebounded the Bruins 36-33 and had 16 turnovers, one less than the visitors, who were led by Dan Oliver, a 6-6 forward who scored 15 points.