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Great Britain flyweight Nicola Adams is guaranteed a medal after winning through to the semi-finals of the Olympic boxing tournament.

Adams, 29, outclassed Stoyka Petrova, beating the Bulgarian 16-7.

However, lightweight Natasha Jonas was beaten by Ireland's Katie Taylor, while Savannah Marshall, the reigning middleweight world champion, also lost.

Middleweight Anthony Ogogo and super-heavyweight Anthony Joshua fight on Monday evening.

Bantamweight Luke Campbell secured GB's first boxing medal by winning his quarter-final match on Sunday.

Leeds boxer Adams was so dominant in her fight on Monday that she even had time to do an Ali shuffle in the final round. "I enjoyed every moment of it," she said.

"I had to get an Ali shuffle in there - I've watched so many of his videos so I thought I'd sneak a cheeky one in. I've got the bronze medal in my back pocket but I want to go for a better colour."

Her next fight is against Indian legend Mary Kom, a five-time world champion who beat Tunisia's Maroua Rahali 15-6.

"You've got to be special to win five world titles," said Adams, who beat Kom in the quarter-finals of the World Championships in May.

"But I'll have height and reach advantages and I'll be using all those attributes. Whatever she does, I'm sure I'll be able to match it."

The atmosphere for the bout between Jonas and four-time world champion Taylor, her country's brightest hope for a gold medal at the Games, was electric, with the noise level reaching 114 decibels, which is just shy of a thunderclap.

The 26-year-old Taylor, from Bray, County Wicklow, raced into a three-point lead after the first round and retained the margin after some furious action in the second.

With the ExCeL Arena bedecked with the Irish tricolour, Taylor poured on the pressure in the third, demonstrating blinding hand-speed and a great variety of shots and eventually forcing a standing count.

Liverpool southpaw Jonas, 28, showed tremendous heart to keep coming forward in the fourth but Taylor, who forced another standing count, simply had too much class.

"People don't realise what a struggle it was to get here and I'm so proud to be boxing in the Olympics and doing women proud," said Jonas.

"When you see women's boxing at the highest level, how can you argue that women aren't as good as the men? I hope Katie Taylor goes on to win it."

Taylor, who has also represented Ireland at football, fights Mavzuna Chorieva of Tajikistan in the last four.

Marshall, 21, her country's first ever women's boxing world champion, looked the more effective fighter in her bout but the judges disagreed.

The turning point was the third round, which she lost 3-1, despite appearing to control the action behind her jab.

Having to chase the fight, Marshall, from Hartlepool, took too many shots in the fourth and ended up losing 16-12.

Three-time world champion Ren Cancan of China, who beat Adams in the 2010 and 2012 world finals, beat Russia's Elena Savelyeva 12-7.

On Sunday, Savelyeva made history by becoming the first woman to win an Olympic boxing match.

The United States, who have only one fighter left in the men's competition, guaranteed two medals through flyweight Marlen Esparza and middleweight Claressa Shields.