Teofimo Lopez backed up years of trash talk on Saturday night, defeating Vasiliy Lomachenko by unanimous decision to become the undisputed lightweight champion at just 23 years old. 

The judges scored the bout 119-109, 117-11, 116-112 in Lopez's favor, per the ESPN broadcast. 

Chris Mannix and ESPN's Max Kellerman felt Lopez (16-0, 12 KOs) deserved the upset victory, displaying poise and precision against a boxer many consider to be the best pound-for-pound fighter in the world:

Ring Magazine's Douglass Fischer took issue with the scorecards but still felt Lopez won:

Lopez controlled the quiet rounds at the MGM Grand in Las Vegas, timing his punches well and not making any clear mistakes for Lomachenko (14-2, 10 KOs) to take advantage of. Even when Lomachenko flipped the switch in the later rounds and attacked, Lopez managed to find ways to stem the tide.

“It’s time for the new generation to come up, and it was time for me to lead the way for everybody,” Lopez said, per Sam Gordon  of the Las Vegas Review-Journal. “So many (young fighters) out there are ready to take over the world.”

The first few rounds clearly went to Lopez, who initiated most of the action. Lomachenko seemed content to give the younger fighter time to reveal his patterns, with his offense popping up late in the second on a slick combination he landed in between Lopez's punches. 

It takes confidence and smarts to let an opponent work without offering much return fire, but that's typically part of Lomachenko's game. However, DAZN's Andreas Hale noted the inherent danger in giving away rounds:

Lomachenko didn't offer much of anything in the fourth and fifth rounds, the spots where he usually establishes himself as the dominant fighter. Lopez didn't do much either, but his intermittent bodywork was enough to take the rounds.

Ring Magazine's Tom Gray felt Lopez's sound technique was getting the better of Lomachenko:

With Lopez holding a clear advantage, the Ukrainian champion finally started to press the action more in the seventh round. Lopez held his ground, landing body punches and then using his reach and the threat of his power to keep Lomachenko from closing the distance or getting off combinations.

The Athletic's Mike Coppinger praised the focused, technically-sound display from Lopez:

Finally, in the eighth round, Lomachenko's offense appeared like a thunderbolt from a clear blue sky. He landed a stinging string of punches halfway through the frame, crowding Lopez and firing from difficult angles.

Top Rank Boxing has the highlights from the eighth:

From that point on, the fight everybody tuned in for had arrived. Lomachenko's jab work was excellent, as he repeatedly snapped back Lopez's neck by going right down the middle. Lopez, who packs more muscle than Lomachenko, started to slow down in the late rounds. The body shots he was throwing early in the fight went by the wayside as he fought to keep Lomachenko from overwhelming him with his speed.

A stunning 12th round saw both fighters land some of their best punches. Lopez had been crumbling for a good five rounds or so, but he found a clearing in the final 30 seconds and rocked Lomachenko with a few great power shots. Here's how some of the round looked, per Top Rank Boxing:

A clash of heads in the final seconds opened up a gash over Lopez's right eye, which led to a somewhat anticlimatic conclusion to the bout. 

Considering Lomachenko's resurgence in the second half of the bout, this result will have many fans clamoring for a rematch. The veteran hit higher highs over the course of the bout, but the upstart was in control for longer stretches.