Olympic champion James DeGale sparkled in a fourth-round stoppage of unbeaten American Brandon Gonzalez on the undercard of the Carl Froch-George Groves rematch on Saturday in London. The British star was sharp from the start, stunning his man with a whipping left hand in the opening seconds, and he continued to apply serious pressure throughout.

In Round 4, DeGale, THE RING's No. 8-rated super middleweight, connected with a sharp combination and as Gonzalez staggered backwards he was tagged by a jolting left hook to the jaw. He rose gamely but DeGale unloaded with huge shots from his southpaw stance and the referee wisely halted the action.

“That is exactly what I wanted to do tonight,” said DeGale, when interviewed by Sky Sports. “The left hand was working and so were right hooks to the chin. This opponent was ready and came to win, but I’m ready for my world title fight now. I don’t care who wins between Froch and Groves, I’m now mandatory challenger to face the winner.”

DeGale improves to 19-1 (13 knockouts) with his sole defeat coming to Groves in May 2011. The official time was 2:38 and both fighters weighed in at 167.5 pounds.

Jamie McDonnell, THE RING's No. 7-rated bantamweight, scored a 10th-round stoppage of Thailand’s Tabtimdaeng Na Rachawat to claim the vacant “regular” WBA title. Rachawat pressured McDonnell throughout and had his fair share of success, but the British technician picked the more accurate punches and relied on his superb conditioning to remain a step ahead.

The end came courtesy of a picture perfect left hook to the jaw. McDonnell, who is orthodox, planted his feet in the southpaw stance, after moving briskly to his left, and landed the knockout shot with full leverage. Rachawat was finished and the referee stopped the bout before completing the ten count.

“I felt at ease in there,” said McDonnell. “I give my opponent credit for coming forward so aggressively but he walked on to one. I got a cut around my left eye, but used my feet to stay out of danger.”

Please note THE RING only recognizes Anselmo Moreno as the WBA champion in this weight class. McDonnell (24-2-1, 12 knockouts) previously held the IBF title, but was stripped for failing to enter negotiations for a mandatory defense.

McDonnell and Rachawat weighed in at 117.75 and 117 pounds respectively.

Former world title challenger Kevin Mitchell, THE RING's No. 6-rated lightweight, overcame stubborn resistance from Ghislain Maduma to post a stirring 11th-round stoppage. Mitchell was pushed hard by his Congolese opponent, who displayed technical superiority for large parts of the contest, and mathematically the stoppage was a necessity.

The end came when the Essex puncher broke through with some solid left hand work which had Maduma woozy. The visitor took a count and Mitchell, who remained calm and composed, found another brisk left uppercut which sent his man down for a second time. The referee inspected Maduma during the mandatory eight count and decided he’d had enough.

“We knew he was a fast starter,” said Mitchell, who improves to 38-2 (28 knockouts). “I had to be professional and get better as the fight went on. He was all over the place at the end.”

The official time was 2:56 and both men weighed in at 134.75 pounds.

At heavyweight Olympic gold medalist Anthony Joshua (236 pounds) easily swept aside a futile challenge from Matt Legg in the first round. Legg attacked from the opening bell, but was dissuaded from getting too ambitious by one memorable combination to the head. The end came courtesy of a well-placed right uppercut and Legg displayed no urgency in terms of beating the count.

“It was brilliant,” said Joshua, in reference to the atmosphere. “I took a few and gave a few, but I knew Legg couldn’t last beyond three rounds. Experience is what I need, but I’m just back after an injury and I’ll be back out on July 12.”

The official time was 1:23.

Tom Gray is a member of the British Boxing Writers’ Association and has contributed to various publications.  Follow him on Twitter: @Tom_Gray_Boxing