Rugby's new scrum law could simply result in the crooked feed replacing the collapse as the source of contention, and penalties, if the first outings at Test level in the Rugby Championship on Saturday were anything to go by.

The International Rugby Board (IRB) introduced the law with the aim of making the game safer for front-row forwards and are hoping for fewer scrum resets and the resultant, often apparently arbitrary, penalties.

The law requires the front rows to be engaged and the scrum steady before the ball is put in, removing the "big hit" of the packs coming together, and promising a more stable set piece.

The first test of the law in action at international level came after 10 minutes of New Zealand's 47-29 victory over Australia at Sydney's Olympic Stadium on Saturday.

The first effort collapsed just as surely as it would have under the old laws and, at the reset, Wallabies scrum-half Will Genia was penalised with a free kick for not putting the ball in straight.

The straight feed has long been a law more honoured in the breach but confusion reigned when All Blacks scrum-half Aaron Smith was allowed to get away with a similarly crooked introduction of the ball at the next scrum.

South African referee Craig Joubert blew up for a crooked feed for around a third of the scrums, leaving Wallabies coach Ewen McKenzie to describe the set piece as a "lottery for both sides".

While there was clearly no sign of the advantage to the Australian front row that some observers had anticipated, Wallabies captain James Horwill thinks the laws will work better once everybody got used to them. "It was a bit of a feeling-out process for everyone, including the referees," said the second-row forward. "Obviously, they're going to be pretty strict on the feed and we will learn from that."

All Blacks coach Steve Hansen, with more than a hint of sarcasm, described the scrums as "great".

"We have just created another issue, haven't we? So once we get that sorted out and half-backs put the ball in straight we'll be fine," he said.

"Obviously at the moment the referees are being very vigilant on it, so you had two sets of half-backs out there who, every time there was a scrum, were very reluctant to put the ball in because they didn't want to be yellow carded."

Another team having their first experience of the new law were Argentina's Pumas, but if it gave them any edge, it scarcely made a difference as they were humbled 73-13 by South Africa in Soweto.

The supporters at Soccer City had to wait less than a minute for the first scrum but it ended in the same way as that in Sydney, with the referee blowing for a free kick.

This was the first of a couple of decisions against the Pumas' front row for not binding properly, by New Zealander Chris Pollock, who was even stricter on the crooked feed than Joubert had been. Everyone expected the new law to take some time to bed in but it looks to be the half-backs, required to bring an end to decades of lobbing the ball under the boots of their locks, rather than props and hookers, who have the most to learn.

"We said there would be teething problems but the great thing is we didn't have too many collapses," Hansen added. "Once we iron out the whole thing and get used to it, I think it will be great for the game."