English middleweight Anthony Fowler reached the last 16 at the World Championships in Almaty, Kazakhstan by overcoming Abdelmalek Rahou.
In the opening round, Liverpool fighter Fowler floored his Algerian opponent on the way to a unanimous points win.
Another middleweight, Scotland's Aston Brown, also progressed after beating South Korea's Jeong Jae-Min.
Welsh light-flyweight Ashley Williams was knocked down early but recovered to defeat Malith Muthikarage of Sri Lanka.
Super-heavyweight Joe Joyce, from London, was stopped in the first round by Algeria's Hamza Beguerni, while Leeds light-flyweight Jack Bateson was beaten by Costa Rica's David Rodriguez on a split decision..
Meanwhile, Republic of Ireland middleweight Jason Quigley survived a first-round cut to secure an impressive majority decision win over experienced Indian fighter Vijender Singh.
Of the other Republic fighters in action, Michael Conlan - an Olympic bronze medallist at flyweight but now fighting at bantamweight - saw off Hungary's Kriszthan Nagy, but heavyweight Con Sheehan was defeated by Cuba's Yohanndi Ortega.
However, Scottish trio Aqeel Ahmed,Joe Ham and Ross Henderson all suffered unanimous points defeats.
Ahmed lost to India's Nanao Thokchom, Ham to Ukraine's Mykola Butsenko and Henderson was beaten by Sallah Muhamed of Sweden.