Struggling against a huge underdog, Billy Joe Saunders punched his way out of a potential problem Saturday night.

The brash British southpaw knocked down Marcelo Coceres three times in the 11th round and knocked out the tougher-than-advertised Argentinean challenger. Referee Ray Corona stopped their fight at 1:59 of the 11th round, as soon as Coceres hit the canvas for the third time.

Before Saunders stopped him, Coceres surprisingly made their scheduled 12-round fight for Saunders’ WBO super middleweight title competitive. England’s Saunders (29-0, 14 KOs) was listed as a 100-1 favorite by several Internet sports books entering their bout on the Logan Paul-KSI undercard at Staples Center in Los Angeles.

“Look, there’s no excuse,” Saunders told DAZN’s Chris Mannix regarding his U.S. debut. “That performance [is] not worthy of the Canelos, the Jacobs and the other big names. I came here five days before [the fight]. I’m not making excuses, but I knew, in my own heart, from round nine I have to get this man out of there. I thought I have to get him out because my timing were off, my head movement were off. Everything was just off tonight. It’s just one of them nights. I won, but you know, I wanted to impress the American crowd. I hope you enjoyed the knockout, because that’s the only thing I can give you tonight. So, thank you very much.”

Saunders made the first defense of the WBO super middleweight title he won nearly six months ago.

The 30-year-old Saunders won the then-unclaimed WBO 168-pound championship in his previous fight. The former WBO middleweight champ convincingly out-boxed Serbia’s Shefat Isufi (27-4-2, 20 KOs) in that 12-rounder and won a unanimous decision May 18 in Stevenage, England.

Coceres (28-1-1, 15 KOs) fought as a full-fledged super middleweight for the first time in his seven-year pro career. He also boxed his best opponent by far, but he gave a commendable account of himself versus Saunders and made their fight tight.

Coceres had gained momentum by the 11th round, but Saunders knocked him down 37 seconds into it after landing a right-left combination. Coceres got up quickly, but then took a knee before answering Corona’s count.

A right uppercut by Saunders floored Coceres again with 1:32 to go in the 11th. Coerces again got up and tried to fend off Saunders, but Saunders dropped him a third time with a left hand.

That’s when Corona waved an end to the action.

Fans began booing early in the 10th round, as Saunders and Coceres moved around, without throwing many punches. A right uppercut-left hook combination by Coceres landed with just under 20 seconds remaining in the 10th.

A right uppercut by Coceres caught Saunders just before the midway mark of the ninth round. Coceres connected with a straight right hand a little later in the ninth.

Coceres landed four right hands in the middle minute of the eighth round, but Saunders walked through all those shots. Saunders drilled Coceres with a straight left hand in the eighth, but Coceres also took that punch well.

A right-left combination by Saunders landed in the center of the ring with just under a minute to go in the seventh round. Coceres landed hard rights to the body before Saunders landed that combination.

Coceres caught Saunders with two right hands just before the sixth round ended. Coerces was the busier, more accurate fighter in the sixth round as well.

With just over a minute remaining in the fifth round, Saunders landed a left, then a right, then a left in what was his best sequence of the fight to that point.

For the second time in the bout, Corona warned Saunders for fouls in the fourth round.

He hit Coceres low with a left hand just after the midway mark of the fourth. Saunders also came forward and hit Coceres after Corona instructed Saunders to go to a neutral corner while Coceres recovered from the low blow.

Coceres connected with a straight right hand with just over a minute remaining in the third round. A straight left hand by Saunders backed Coceres into the ropes with 25 seconds to go in the third.

Saunders clipped Coceres with a right hook to the head and followed with a right to the body just before the two-minute mark of the second round. Corona warned Saunders for a low blow with just under two minutes to go in the second round.

Coceres caught Saunders with a hard, right hand with 1:15 to go in the first round.

Saunders controlled the final minute of the opening round with his jab. He also clipped Coceres with a left uppercut toward the end of the first round.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.