Tatum scores record 55 to lead Team Giannis in NBA All-Star win
Both namesake captains made early exits with injuries, James after bruising his right hand on the rim making a dunk and Greek star Antetokounmpo with a right wrist sprain suffered three nights earlier.
That left the starring roles up for grabs and the All-Star Game Most Valuable Player award went to Boston star Tatum, who broke the old NBA All-Star Game record of 52 points scored by Anthony Davis in 2017.
"It means the world," Tatum said. "You think of all the legends and great players that have played this game.
"Records are made to be broken so I'll hold it for as long as I can but I'm certain somebody will come along in a couple years and try to break it."
Tatum made 22-of-31 shots from the floor, 10-of-18 from 3-point range and added 10 rebounds, six assists, a steal and a blocked shot.
Tatum scored a record 27 points in the third quarter to lift Team Giannis ahead 158-141 entering the fourth quarter.
"You see the first three go in and keep shooting, just stay hot and just keep running," Tatum said.
A unique rule featured an untimed final quarter with a "target score" set to decide a winner - the total for the team leading after three quarters plus 24 points.
Whichever club reached that number first won, setting a goal for both teams of 182 points.
Tatum sank a free throw to reach 53 and break the record, giving Team Giannis a 177-162 lead.
Tatum added a layup to put his club a single point from victory at 181-170 and moments later Damian Lillard sank a final 3-pointer to deliver the victory.
Giannis had been 0-2 as a captain but was delighted to hoist the trophy despite a sore wrist.
"Winner. Winner. Chicken dinner," Antetokounmpo said.
Cleveland's Donovan Mitchell added 40 points and 10 assists for Team Giannis while Portland's Lillard had 26 off the bench.
Team LeBron reserve Jaylen Brown of Boston had a team-high 35 points plus 14 rebounds. Philadelphia's Joel Embiid and Kyrie Irving of Dallas each added 32 points, with Irving adding a game-high 15 assists.
Four-time NBA champion and NBA Most Valuable Player James set a record by playing in his 19th All-Star Game but suffered a bruised right hand hitting the rim while making a dunk and sat out the second half.
The Los Angeles Lakers superstar finished with 13 points on 6-of-11 shooting with four assists and a rebound. He was able to manage numerous handshakes in a half-time ceremony in tribute to his scoring mark.
Milwaukee big man Antetokounmpo made a dunk for the game's first points before leaving for good seconds later due to a sprained right wrist suffered in a regular-season game on Thursday.
"It's just hard. I love competing," Antetokounmpo said. "I wasn't able to participate for the full thing but I wanted to go out there even for 10 seconds, sweat a little bit in the jersey, because I want to be part of this."
Lillard's half-court 3
Team Giannis led 99-92 at halftime with Tatum scoring 17 points and Irving leading Team LeBron with 18.
Lillard, the 3-Point Contest winner, sank a 3-pointer from just beyond the half-court line to highlight a third quarter dominated by deadly NBA sharpshooters.
James fell to 5-1 as an All-Star captain since the format began in 2018, having won twice over Kevin Durant and Antetokounmpo and once over Stephen Curry.
Miluwakee big man Antetokounmpo from Greece and Los Angeles Lakers playmaker James, who earlier this month became the NBA's all-time scoring leader, were named captains after being the top vote-getters for All-Star starting spots from the Eastern and Western Conferences.
Captains picked their rosters only minutes before tipoff.
James selected Cameroonian big man Enbiid with his first pick while Antetokounmpo selected Tatum next.