Michael Katsidis stunned the 20,000 fans at Upton Park
By Ben Dirs
BBC Sport at Upton Park
Kevin Mitchell's dream fight at Upton Park turned into a nightmare as he was dismantled inside three rounds by Australian Michael Katsidis.
Mitchell, 25, looked surprised by Katsidis' power in the first round and was immediately forced to backpedal.
The Dagenham man appeared to have settled in the second, finding his mark with some sharp combinations.
But Katsidis, 25, staggered Mitchell with a big left hand in the third and referee Dave Parris later stepped in.
"I knew he was a big puncher, I knew he was heavy-handed," said Mitchell.
"He lured me into an attack and bang, he caught me.
"I've been in with big punchers - Carl Johanneson, Breidis Prescott. He lured me into the shot, I walked into one and bang. You can't make mistakes like that, I made the mistake and that's that.
"It's a wake-up call, I've got to be more professional in what I'm doing and take more care of my work and be more aware of what I'm doing in the ring, I backed up and sat on the ropes like an idiot.
"I'll be back and I'll be strong and I'll be ready to fight him again, definitely. 100% I will win a world title, I promise you."
Mitchell was challenging for Katsidis' WBO interim lightweight crown in front of 14,000 vociferous locals at West Ham's ground, but it was the Aussie who seemed the more energised by the occasion.
Punk band Cockney Rejects were on hand to sing Mitchell into the ring with a raucous rendition of the old Hammers favourite I'm Forever Blowing Bubbles, but Katsidis, in his trademark gladiator helmet, looked noticeably bigger when they eventually came face to face.
And after a cagey opening, Mitchell seemed to be somewhat taken aback when Katsidis decided to break ranks, with the Englishman spending most of the rest of the round on the back foot and Katsidis landing some spiteful blows.
It was better from Mitchell in the second, the challenger using his jab and finding the target with some snappy combinations, but still Katsidis came pouring forward.
At the start of the third Katsidis seemed to back off slightly, which succeeded in luring Mitchell forward into a slugging match and allowed the champion to pounce.
Former British and Commonwealth super-featherweight champion Mitchell, who made his name as a slugger, had looked a more complete fighter in his last few fights, and the accepted wisdom was that he should avoid going toe-to-toe with Katsidis.
And sure enough, when the leather started flying it was the champion who came off best, staggering Mitchell with a cuffing left to the back of the head, a shot from which Mitchell never really recovered.
Mitchell fired back with a couple of combinations, but Katsidis just kept coming, backing his rival onto the ropes before landing with another clubbing left and following up with a sustained, two-fisted battery.
And with Mitchell no longer returning fire, Parris was left with no other option but to stop the fight one minute and 57 seconds into the round, an outcome that stunned the West Ham faithful into virtual silence.
It's fantastic, it's been an absolute pleasure
Mitchell, who was previously unbeaten in 31 pro encounters, will now have to rebuild his career, with a much talked about domestic match-up against Amir Khan now a distant dream.
While he vowed to come back and win a world championship, the manner in which he was exposed by a fighter who had fought and come up short at the very highest level will raise questions about his ability to do so.
But promoter Frank Warren has backed his man to return from his first loss and follow Khan's example by bouncing back from defeat to win a world title.
"Can he come back? I think he can," Warren told BBC Sport.
"We saw what happened to Amir Khan 18 months ago, and it's all about him using the talents he's got and not letting his heart overrule his brain.
"If he does that again he won't win a world title, he's got to learn and he's young enough to do that. He's got to go back to the drawing board and if he can learn, I think he will win a world title."
Instead it is Katsidis, who stopped Luton's Graham Earl in five savage rounds when he last fought in London in 2007 and who improves to 27 wins and two losses, who can now look forward to some big pay days, with the WBO's full champion Juan Manuel Marquez still on his radar.
"It's fantastic, it's been an absolute pleasure. You've got 20,000 people here, I would just hope one day these people could come and support me," said Katsidis.
"I feel I'm the best I've ever been, we've worked hard and I've been away from my family and my new baby girl.
"I can't leave Britain anyway because of the volcano, so I just want to stay here. There's 20-odd thousand passionate people here cheering and supporting the sport I love.
"I'm just going to enjoy my title, I am the world champion."