Italy dethroned the defending champions South Africa to cause one of the biggest upsets in the history of the World Rugby Classic at North Field last night.

In a true display of grit and determination, Rugby Italian Classic defeated the Classic Springboks 31-17 to advance to the semi-finals for the first time at their seventh attempt.

The Springboks will now join another fallen giant, the Classic Lions — still licking their wounds after an opening day reverse by France — in the consolation competition.

For Italy, a mouth-watering semi-final against the All Blacks awaits, with Marcello Cuttitta, the team’s president, backing his history makers to claim another prized scalp on Thursday night.

“This is a very important win for us,” said Cuttitta, who won 54 caps for his country.

“It’s our seventh year here and the first time we’ve reached the semi-final. We showed a lot of courage and heart. It’s the All Blacks next and we have to go all of the way!”

Early tries from Andrea Barbieri, Ramiro Paz and Juan Sebastian Francesio — all converted by Paz with metronomic efficiency — left a surprisingly sluggish South Africa looking shell-shocked.

Things then went from bad to worse for the six-times winners when they conceded a penalty try, which Paz also kicked home to give his team an unimaginable 28-0 lead after just 20 minutes.

“I don’t think they expected us to come out like that,” Cuttitta added. “It was very important for us to make a strong start.”

Italy, so often the whipping boys, were showing signs of fatigue as the first half wore on, unsurprising given the gusto in which they had taken the game to the Springboks.

Even so, it still took until the 26th minute for South Africa to register their first try, with wing Tonderai Chavhanga — one of their heroes in last year’s final — crashing through the backline.

South Africa then let Italy off the hook in perhaps the flashpoint of the game when, in a two-on-one situation on the Italian goal line, a pair of South Africans conspired to fumble the ball when it seemed easier to score.

Looking far more focused after the break, the Springboks placed Italy under sustained pressure as they pushed and attempted to gain a foothold back in the game.

But the Italians were in no mood to relinquish their advantage, defending like their lives depended on it, as they spent a staggering nine minutes virtually camped on their goal line.

They appeared to have weathered that particular storm before Reinhard Gerber started and finished a superb move to spark his South Africa back into life in the 43rd minute.

By now South Africa’s tails were up and the pendulum looked to be swinging back in their favour when Danny Coetzee added his team’s third try, which Monty Dumond kicked to make it 28-17.

The Italians were in danger of slowly unravelling until they were awarded a pressure-relieving penalty with about five minutes remaining.

Paz showed nerves of steel, as he had all night long, to add three points and open up an unassailable 14-point lead.

“When we placed I knew we had won the game,” Cuttitta said. “It was important for the score and for the minds of the players.”

Mark Wood, the South Africa manager, said his team’s “dismal line-outs” proved costly in the first half and made a rod for their own backs with some sloppy play.

“Just before half-time we had a guy go over the try line but he didn’t knock it down and that would have created more momentum,” Wood said.

“All credit to [Italy], this is rugby, and sometimes things go wrong for you. We will show character and show people what we’re made of on Thursday [against USA Eagles].”

• Andy Haden, the All Blacks manager, has warned his side they must improve after making hard work of their 31-13 win over the USA Eagles in last’s night opening game.

The Kiwis fell behind in 20th minute when flanker Garret Peterson forced his way through the middle to give his side a deserved lead, having controlled much of the first half.

New Zealand struck back almost immediately through lock Tom Donnelly, diving in at the corner and Willy Walker converting, before adding another try just before half-time through Rhys Bennett.

The Classic Eagles pulled back to 12-10 when Maximo de Achaval kicked home a penalty soon after the restart, although the New Zealanders replied again when Brad Tauwhare scored his side’s fourth try to make it 19-10.

Another penalty by De Achaval reduced the deficit for the Eagles, but further tries by Walker and Brendon Ward put the game beyond doubt for the much-fancied All Blacks.

“We were a bit average and took a long time to get going,” Haden said. “But when you sit on a plane for 36 hours that can happen.

“It will take a little time to get a rhythm and get our combinations going. I don’t think we will get worse.”

Haden added: “USA were up for it. I guess it was the game of their lives.”