RingTV.com will do live round-by-round updates of tonight's welterweight bout during which Keith "One Time" Thurman scored a second-round knockdown on the way to a third-round technical knockout victory over two-time lightweight titlewinner Julio Diaz, whose corner stopped the fight due to a rib injury before the fourth round at the StubHub Center in Carson, Calif.

The 25-year-old Thurman (23-0, 21 knockouts) scored his third straight stoppage win against the 34-year-old Diaz (40-10-1, 29 KOs).

In his previous fight, Thurman scored knockdowns in the fifth and final rounds of a ninth-round technical stoppage victory over Jesus Soto Karass in December. Prior to Soto Karass, Thurman scored a 10th-round knockout of previously unbeaten Argentine Diego Chaves, whom he dropped once each in the ninth and final rounds to end the loser's streak of five consecutive stoppage wins last July.

Diaz is 0-3-1 in his past four fights, but three of those bouts were a draw and a unanimous decision loss against unbeaten current IBF welterweight beltholder Shawn Porter and a close decision setback to former 140-pound titleholder Amir Khan.

The Showtime broadcast began at 9:30 p.m. ET/PT

Thurman vs.Diaz

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Referee: Jack Reiss

Judges: Raul Caiz Sr., Alejandro Rochin, Robert Hoyle

THURMAN WINS BY TECHNICAL KNOCKOUT!!!

1. Thurman's coming forward behind his jab. Lands two and a left and right to the body. Diaz comes with his hook. Thurman fires and lands another. Double-jab by Thurman. Left hook by Thurman. Double jab by Diaz. Right and a left from Thurman and a jab. Solid up-jab and a right both by Thurman. Right and left by Thurman. Solid shots. Another left hook by Thurman. Thurman slips a right and a left. Left hook by Thurman. Right, left, right, left, all in retreat by Thurman, who took a right to the chest during that sequence. Thurman, 10-9.

2. Two jabs by Thurman and a left by Diaz. Left hook by Thurman and a jab. Jab to the head by Thurman, one to the body from Diaz. Right over the left by Thurman. Hard right hand and a left that started it by Thurman off the counter. Two jabs and a right by Thurman. Diaz whiffs a hook. Right by Thurman. Triple-jab by Thurman. LEFT UPPERCUT WOBBLES DIAZ. Back to the jab for Thurman. Right hand by Thurman. Lead left by Thurman. LEFT HOOK TO THE TEMPLE DROPS DIAZ AS A DELAYED REACTION. He's up at the count of eight by referee Jack Reiss. Takes a left and a right from Thurman. Thurman, 10-8; Thurman, 20-17.

3. Left hook by Thurman early. Jab and right by Thurman and a nice up-jab by Thurman. Right by Diaz over the top. Hook by Thurman. Double-right cross by Thurman. Right to the head by Thurman. Left hook by Thurman. Jab by Thurman. Right hand by Thurman on the ropes. Thurman has his hands at his side. Posing. Left hook by Thurman. Triple left hook by Thurman, who dances away. Hard right hand by Thurman to the body.  Series of left hooks appear to stun Thurman. Right hand, left hook, right hand all by Thurman. Thurman, 10-9, 30-26

FIGHT'S OVER: JULIO DIAZ'S CORNER STOPS THE FIGHT DUE TO A RIB INURY.

THURMAN WINS BY TECHNICAL KNOCKOUT!!!