Seven days’ notice. Seven-to-one underdog. Five rounds to change everything.
Sergio “Yoreme” Mendoza walked into Wintrust Arena in Chicago as a last-minute substitute and walked out as WBC World Flyweight champion, stopping Ricardo “El Niño” Sandoval via TKO in round five on October 10, 2026. Three knockdowns, a systematic dismantling on the CompuBox numbers, and the upset of 2026.
| Detail | |
|---|---|
| Winner | Sergio Mendoza |
| Method | TKO (Round 5, 1:46) |
| Scorecards at stoppage | 36-38, 36-38, 36-38 (all three judges had Mendoza ahead) |
| Title | WBC World Flyweight Championship |
| Venue | Wintrust Arena, Chicago, Illinois |
| Date | October 10, 2026 |
| Promotion | Golden Boy Promotions / Most Valuable Promotions |
| Broadcast | DAZN (US and global) |
Referee Mark Nelson waved it off at 1:46 of the fifth after Mendoza put Sandoval down for the third time and Sandoval had nothing left to offer. Every judge had the challenger in front when it ended.
Oscar Collazo withdrew with a rib injury three weeks before fight night. Sandoval’s team accepted Mendoza as a replacement. On paper, that looked reasonable: Mendoza had just been stopped in two rounds by IBF light flyweight champion Thanongsak Simsri six months earlier in Tokyo. He came in ranked outside the top five. DraftKings installed Sandoval as a 7-1 favourite.
What the odds missed was the physical mismatch created by the switch. Collazo stands 5’2” and was moving up from 105 lbs. Mendoza is 5’8” and a career flyweight with 24 professional stoppages. Sandoval, who had spent months preparing to work inside on a miniature southpaw, instead faced a taller, longer, harder-punching challenger with 85% career stoppage rate.
The CompuBox numbers recorded that misalignment punch by punch.
| Round | Mendoza landed / thrown | Sandoval landed / thrown |
|---|---|---|
| 1 | 6 / 29 | 6 / 28 |
| 2 | 16 / 47 | 10 / 36 |
| 3 | 16 / 62 | 8 / 40 |
| 4 | 14 / 57 | 19 / 57 |
| 5 | 11 / 30 | 6 / 22 |
| Total (R1-5) | 63 / 225 | 49 / 183 |
Mendoza out-landed Sandoval 63 to 49 across the five completed rounds, throwing 42 more punches in the process. The power punch differential was the real story: Mendoza landed 54 power punches at 40% accuracy, against Sandoval’s 42 at 29.4%. When the southpaw connected, it registered.
Round two was the turning point. A right hook to the top of Sandoval’s head sent the champion to the canvas with 1:39 remaining. He rose, but Mendoza was straight back on him, landing a vicious left uppercut to the chin with 18 seconds to go that put Sandoval down a second time in the same round. The champion got up, survived, and came out for round three, but he was fighting hurt.
Round four was Sandoval’s best — the CompuBox records 19 landed punches to Mendoza’s 14, the only round where the champion outscored the challenger. It briefly made the crowd believe. Then the fifth opened and Mendoza landed a counter right hook that sent Sandoval down to his gloves and one knee. When Sandoval rose, Mendoza drove him into the ropes with a sustained attack and Nelson stepped in at 1:46.
It was the first knockout loss of Sandoval’s 30-fight career.
| Sergio Mendoza | Ricardo Sandoval | |
|---|---|---|
| Age | 26 (b. March 28, 2000) | 27 (b. February 5, 1999) |
| Nationality | Mexico | USA |
| Height | 5’8” / 173 cm | 5’6” / 168 cm |
| Reach | 67.3” / 171 cm | 66.9” / 170 cm |
| Stance | Southpaw | Orthodox |
| Record (pre-fight) | 27-1, 23 KOs (85%) | 27-2, 18 KOs (67%) |
| Total rounds | 115 | 172 |
| Title fights | 1 (0-1) | 1 (1-0) |
Mendoza carried a two-inch height advantage and the experience of a natural 112-pounder — Sandoval carried 57 more rounds in the bank and a title belt. The physical edge proved decisive.
| Date | Opponent | Result | Method | Round |
|---|---|---|---|---|
| Apr 2026 | Thanongsak Simsri | Loss | KO | 2 |
| Nov 2025 | Sandile Tshabalala | Win | KO | 3 |
| Jul 2025 | J.R. Cordova | Win | UD | 10 |
| 2024 | David Martinez | Win | TKO | 4 |
| 2024 | Elvin Ramos | Win | KO | 3 |
The Simsri loss looks alarming in isolation. In context, Mendoza had been fighting at 108 lbs (light flyweight) for a world title shot — Simsri’s division, not his. At 112 lbs, where he belongs, he had four wins by stoppage in his previous five fights before the Tokyo trip. Coming back to flyweight appeared to give him his full power back.
| Date | Opponent | Result | Method | Round |
|---|---|---|---|---|
| Jul 2025 | Kenshiro Teraji | Win | SD | 12 |
| Feb 2025 | Jesse Henderson | Win | UD | 10 |
| Jul 2024 | Joselito Acosta | Win | KO | 10 |
| Mar 2024 | Joshua Buitrago | Win | TKO | 8 |
| 2023 | Cesar Santomauro | Win | UD | 10 |
Sandoval arrived with a five-fight unbeaten run that included a split decision upset of Kenshiro Teraji in Japan to claim the WBC flyweight belt. The issue the form line doesn’t show: a 15-month layoff between the Teraji win and this fight, and preparation for a completely different opponent. According to Ring Magazine’s Keith Idec, Sandoval had spent weeks preparing for Collazo’s style — a 5’2” southpaw, not Mendoza’s 5’8” frame.
Oscar De La Hoya, speaking to BoxingScene immediately after the stoppage, confirmed Mendoza had roughly seven days’ notice to replace Collazo. That timeline did not visibly affect his preparation. He came in sharp, heavy with power, and better suited to the matchup than Collazo would have been on paper.
Mendoza told reporters he had been training in isolation, away from family, focused entirely on the task: “I have no family, no friends, but I’ve got my team and I was focused to win.” He dedicated the victory to a brother who had recently passed away.
Sandoval, for his part, managed to rally in round four — the CompuBox confirms he out-landed Mendoza in that round. The problem was the cumulative damage from the two second-round knockdowns, and a challenger whose power punch accuracy never let up. Sandoval’s own power accuracy never reached 30% in any five-round stretch. Mendoza’s sat at 40% for the fight and reached 57.9% in round five.
Mendoza (28-1, 24 KOs) is now WBC World Flyweight champion. The WBC’s interim flyweight titleholder, Olympic gold medalist Galal Yafai, is the most logical next mandatory challenger within the division. Whether Mendoza moves straight into that defense or the WBC orders an eliminator first will set the agenda for 2027.
Sandoval (27-3, 18 KOs) suffers his first stoppage loss after ten professional years. His record still shows significant wins — the Teraji upset was legitimate — but a 15-month layoff followed by a TKO to a replacement opponent raises durability questions heading into any title rematch conversation.
Oscar Collazo, who withdrew due to a rib injury, would have been a WBO 105 lb champion stepping up two divisions. The Ring’s report suggests Mendoza’s result may make Collazo reconsider whether that fight still makes sense.
Wintrust Arena also crowned a new WBA Lightweight champion the same night — Floyd Schofield defeated Lucas Bahdi by unanimous decision in the main event. Read the Schofield vs Bahdi result and review for the full breakdown.
Who won Mendoza vs Sandoval? Sergio Mendoza won by TKO in round five, stopping Ricardo Sandoval at 1:46 of the fifth round to claim the WBC World Flyweight title.
How many knockdowns were there? Three. Mendoza dropped Sandoval twice in the second round — a right hook and a left uppercut — and once more in the fifth round before referee Mark Nelson stopped the fight.
What were the scorecards? All three judges had Mendoza ahead at the point of stoppage: 36-38, 36-38, 36-38.
What title was at stake? The WBC World Flyweight Championship (112 lbs).
Why was Mendoza such a heavy underdog? He had been stopped in two rounds by IBF light flyweight champion Thanongsak Simsri six months earlier, and stepped in as a late replacement for Oscar Collazo with approximately seven days’ notice. DraftKings opened Sandoval at 7-1 favourite.
What were the CompuBox totals? Over five rounds, Mendoza landed 63 of 225 total punches (28%), including 54 of 135 power punches (40%). Sandoval landed 49 of 183 (27%), including 42 of 143 power punches (29.4%). Mendoza’s 40% power punch accuracy compared to Sandoval’s 29.4% was decisive.
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