For most of the first 20 minutes Monday night, the UCLA men's basketball team looked like one that won't be unranked for long.
However, in the second half against No. 4-ranked Marquette, the youth and inexperience of a Bruins team playing at full strength for the first time this season was apparent, too.
UCLA let a 12-point second-half lead slip away, as a 17-0 run keyed Marquette's 71-69 win on the opening night of the Maui Invitational at the Stan Sheriff Center in Honolulu.
The Bruins (3-1) got a game-high 25 points from Sebastian Mack, but his potential game-tying shot at the buzzer misfired.
The Golden Eagles (4-0), who will face top-ranked Kansas on Tuesday, were led by David Joplin's 19 points. He made 5 of 11 3-point shots for Marquette, which shot 54.2% from the field in the second half.
UCLA will face host Chaminade in the loser's bracket Tuesday at 2 p.m. PT.
Turning point of the game
UCLA led by as many as eight early before taking a 35-30 lead into the break.
The Bruins extended the advantage to 45-33 on a Mack jump shot with 15:03 to play, but a 17-0 Marquette run put UCLA in a 50-45 hole. It was the Golden Eagles' first lead since the 18:38 mark of the opening half.
Bruins freshman reserve Ilane Fibleuil ended the drought on a 3-pointer to pull within 50-48 at the 10:37 mark. From there, UCLA chipped away as fellow reserve guard Will McClendon tied the game 59-59 on a 3-pointer with 5:59 left to set the stage for the finish.
The Bruins quickly fell behind again by as many as five before Mack tied the game 64-64 on a traditional three-point play. They took a brief 69-68 lead after teammate Lazar Stefanovic made a steal that led to Adem Bona's go-ahead basket with 53 seconds left.
Marquette guard Sean Jones answered on the next possession with an uncontested 3-pointer for the game's final margin.
UCLA had a pair of chances to tie or take the lead, including a Stefanovic missed 3-pointer that was rebounded by Mack. His drive down the left side of the lane was then contested by 6-foot-11 Golden Eagles forward Oso Ighodaro on the game's final shot.
UCLA standout on offense: Guard Sebastian Mack
From the outset, Mack showed an aggressiveness attacking the rim and was a big reason for UCLA's early success.
He finished 6 of 14 from the field and 13 of 13 at the free-throw line to go with six rebounds and a pair of steals.
UCLA standout on defense: Forward/center Adem Bona
The sophomore was his typical self, contesting anything and everything within his wingspan.
Bona had a pair of blocks and altered a handful of other Marquette drives.
UCLA play of the game
Bona had a few highlights, but none more impressive than a dunk over Marquette guard Kam Jones, who attempted to draw a charge during a frantic back-and-forth sequence not long after the Golden Eagles' difference-making run.
Why UCLA lost
While the Bruins looked like a future top-25 team, the blown second-half lead showed the inexperience of a group that played its first game with freshman Berke Buyuktuncel.
The 6-foot-9 forward from Turkey got the start in his first career collegiate contest.
UCLA turned the ball over 14 times and sent Marquette to the free-throw line on 18 occasions, including 14 after halftime. The Golden Eagles had a 14-7 advantage in points off turnovers and 10-4 edge in second-chance points.
