Saturday night's action featured No. 1 pick Ben Simmons and No. 2 Brandon Ingram facing off in front of a raucous Las Vegas crowd.
But two sophomores took over late, including D'Angelo Russell, who hit a buzzer-beating 3-pointer as the Lakers beat the Sixers 70-69.
Grades for 11 up-and-coming players from Day 2 of the Las Vegas Summer League:
After averaging 19.2 points following the All-Star break as a rookie, Booker is overqualified to play in Las Vegas, and he showed it during Saturday's opener for the Suns.
Booker was automatic when open beyond the arc, making three triples in five attempts, and also showed improvement creating his own shot off the dribble and setting up teammates en route to 28 points, 8 rebounds and 6 assists. Eleven of those points came in a stretch of less than three minutes during the third quarter.
Dragan Bender, Phoenix Suns: A-
The No. 4 overall pick was more impressive than his stat line (12 points and seven rebounds) would suggest. While he couldn't find the touch from beyond the arc, missing six of his seven 3-point attempts, Bender impacted the game in many other ways.
He was effective with the ball in his hands, pushing the ball off defensive rebounds and beating defenders off the dribble to set up good scoring opportunities. Bender also knocked down a couple of hook shots.
Jaylen Brown, Boston Celtics: D+
After missing Boston's past two games in Salt Lake City with a hyperextended knee, Brown returned with another inefficient performance. He shot just 3-of-13 from the field en route to nine points.
Unlike in his first summer game, Brown wasn't able to draw fouls on his forays to the rim, and he struggled to convert inside. That left Brown dependent on his inconsistent jumper.
At the defensive end, Brown remained overly aggressive against pump fakes, leading to fouls and breakdowns.
Marquese Chriss, Phoenix Suns: D
While Bender and Booker impressed, it was a rough start for Phoenix's other lottery pick. Chriss missed eight of his 10 shot attempts, forcing things with the ball in his hands and struggling to finish around the rim despite his impressive athleticism -- including three shots that were blocked.
The reviews were worse defensively; Chriss frequently found himself out of position and got caught reaching the wrong way when defending one-on-one.
Brandon Ingram, L.A. Lakers: C-
The night after an impressive debut, Ingram didn't nearly have the same impact in his second game. He didn't make his first basket until hitting a jumper with just under six minutes left in the fourth quarter and finished 3-of-12. One of those makes was a jumper with his foot on the 3-point line.
Ingram's ability to push the ball on defensive rebounds remained valuable, but the Philadelphia 76ers had Jerami Grant pick him up full court to expose Ingram's need to improve his handle under pressure.
T.J. McConnell, Philadelphia 76ers: B+
It was McConnell, not No. 1 pick Ben Simmons, who had the ball in his hands late in the game. McConnell made a layup with 1.8 seconds left that looked like the game winner, and he celebrated with an aggressive fist pump, emblematic of how hard McConnell played all game.
At times, he got in trouble by turning the ball over while attempting to make a highlight play, but overall, it was a strong effort from McConnell.
Larry Nance Jr., L.A. Lakers: A
Nance had one of the craziest stat lines you'll ever see in any basketball game: 13 points, 8 rebounds, 7 steals, 4 assists and 4 blocks.
According to Basketball-Reference.com, Hakeem Olajuwon and Gerald Wallace are the two players to match or exceed each of those numbers (in a regular-season NBA game) since 1983-84.
While the Lakers-heavy crowd at Thomas & Mack loved all of it, a pair of powerful Nance dunks drew the loudest chants of "Larry! Larry!" (an NBA summer league tradition at this point) and even "MVP!" Nance's game was marred only by his five turnovers.
Bobby Portis, Chicago Bulls: B+
Portis was dominant during the first half, scoring 15 of his 17 points. As he did last year in Las Vegas, Portis showed comfortable NBA 3-point range. And unlike most players during summer league, Portis plays hard, helping him pile up 13 rebounds.
During the third quarter, Portis matched up one-on-one against Brown and generally got the better of him, though he didn't finish after losing Brown on an up-and-under.
D'Angelo Russell, L.A. Lakers: B
After making the winning shot, Russell told the ESPN2 audience, "I played like (expletive)" in the first half. That's true -- Russell was 2-of-9 from the field with five turnovers before halftime. But all was forgiven after his late heroics.
The winning 3 was off the dribble, just like Russell's other two successful long shots in the second half. That ability to pull up off the pick-and-roll may ultimately force defenses to trap Russell and put themselves in a bad spot defensively, along the lines of players like Stephen Curry and Damian Lillard.
Alas, Russell will have to put in more effort to stay in front of his man defensively. He was victimized by many of McConnell's drives.
Ben Simmons, Philadelphia 76ers: B+
Both the strengths and weaknesses of Simmons' game were on full display during his debut in Vegas. On the plus side of the ledger, Simmons came within two assists of a triple-double and threw a series of incredible passes. He threaded the ball between defenders for a McConnell layup and then started a sequence that saw McConnell feed a teammate for a 3.
Yet much as he did in Utah, Simmons struggled to finish around the basket -- particularly when going left, since he's a right-handed finisher despite shooting jumpers left-handed. And his tendency to look for the highlight play resulted in seven turnovers. Overall, though, Simmons added much more than he subtracted.
Denzel Valentine, Chicago Bulls: D
Valentine started his first game by finding center Cristiano Felicio from midcourt for a layup. That was about as good as it got for Valentine, who simply could not find the range from the NBA 3. A 44 percent 3-point shooter last season at Michigan State, Valentine missed all nine of his long-range tries on Saturday.
Turnovers were also costly for Valentine, who coughed it up four times.