The Wexford-born welter, who boxes out of Katie Taylor’s Bray BC, stunned the Russian, who has qualified for Rio 2016 through the World Series of Boxing (WSB) this year, on a unanimous decision (29-28,29-28,29-28).
The first two rounds against Butaev, a silver medalist at the Irish Amateur Boxing Association European Youths in Dublin in 2011, were tight, according to Walsh.
“Wexford might not win an All-Ireland hurling title this year, but we might win a European title,” said Ireland’s chief seconds after Wexford native Nolan’s win.
“It was nip and tuck for the first two rounds, but Adam pulled away in the last round against a quality opponent who won all his fights in the WSB. His best performance.
“Adam is now at the stage of his career where he wants to win a major medal. He has the experience of competing at the Olympic Games and the WSB under his belt and he was absolutely top class today.”
Nolan, a London 2012 Olympian, said: “I think I did all the cleaner scoring, even though he was the aggressor through. Delighted to be in the last-eight. He has now beaten two Rio 2016-bound boxers in Samokov.
Joe Ward, the 2011 European champion, also won yesterday in a good day for Irish southpaws. Ward, who had Ireland’s Georgian coach Zaur Antia, Walsh and Eddie Bolger in his corner, outclassed light-heavy Nikoloz Selchniashvili.
The Georgian, who received public warnings for hitting with the inside of the glove and elbowing Ward in the head in the second, dropped a landslide 30-25, 30-24, 30-25 to the Irishman, who embellished a controlled performance with two slick combos in the third.
Nolan and Ward join London 2012 bronze medallist Michael Conlan and Dean Walsh in today’s quarter-finals, or “Qatar-finals”, as the winners will secure at least bronze and qualify for October’s World Championships in Doha, Qatar.
The top six boxers in each weight class (the semi-finalist and quarter-finalists that lose to the eventual finalists) qualify for Doha, which is doubling up as an Olympic qualifier. Conlan meets Danish southpaw Frederick Jensen in the bantam class.
“He’s tall, he had a good win against the Bulgarian in the last round. I can’t let my performance drop below a certain level,” said Conlan, a silver medallist at the 2013 European Elites in Minsk.
Walsh’s Hungarian opponent, Nyeki Georgian, was born in Romania where he won a national title n 2012, while Ward’s opponent, Belarusian Mikhail Dauhaliavets, represented his country at the London 2012 Olympics.
Nolan, after causing one of the upsets of the tournament so far, will also face a Belarusian, Pavel Kastramin, who beat Ballymena’s Steven Donnelly last year.
Thursday is a rest day and the semi-finals and finals will be held on Friday and Saturday.