New Zealand captain Roy Asotasi is likely to miss the upcoming rugby league World Cup after suffering a suspected torn pectoral muscle in his team's dramatic 22-20 loss to the Sydney Roosters at Sydney Football Stadium on Friday night.

The incident occurred in the closing seconds of the game when Asotasi was tackled while carrying the ball and the Rabbitohs camp later suggested their leader could have been the victim of a "chicken wing" tackle.

"We are going need to check the tackle," South Sydney coach Jason Taylor said.

A crestfallen Asotasi was scheduled to undergo an MRI on Saturday, but both he and South Sydney director of high performance Errol Alcott feared the worst.

"It's a suspected pectoral muscle tear, clinically it looks like he's got a deformity there and that suggests there is a muscle tear," Alcott said.

He said it was normally an 18 to 22 week recovery period for that type of injury.

"It was the last run of the game, I got the ball and got tackled and when I got up it just felt weak straight away," Asotasi said.

A break of that duration would sideline the powerful 26-year-old prop from the World Cup, which will be conducted in October and November.

"The chance (of me playing at the World Cup) is pretty slim, I feel the heartbreak already," Asotasi said.

The news was also received with solemnity by the strong New Zealand contingent in the Roosters squad.

"He's in good form at the moment so it's going to be a blow to us," Roosters fullback and New Zealand squad member Sam Perrett said.

Asotasi's anticipated absence from the tournament is yet another blow to the Kiwis.

"He (Asotasi) is one our leaders, Frank Pritchard is in doubt at the moment and we've lost Sonny Bill Williams, but we've still got a lot of good players," Kiwi Sia Soliola.

Roosters coach Brad Fittler was a relieved man after his side almost squandered a 22-0 lead.

"We weren't at our best but there were better signs. We win next week we're in a top four position, so we've got everything to play for," Fittler said.

"We worked really hard for the first 50 minutes ... we didn't get much ball for the last 30 minutes."

Fittler revealed Anasta, who was captain on Friday night, would hold the position for the remainder of the season and would replace regular skipper Craig Fitzgibbon.

"One of the reasons was I was working on giving the back three a spell, I knew Fitzy was going to be on the sideline at stages," Fittler said.

He said he wanted Anasta, who captained virtually all of his teams up until he broke into first grade with the Bulldogs, to have a bigger say in the game plan.

The Roosters led 14-0 at halftime following tries to winger Amos Roberts, centre Mitchell Aubusson and second-rower Andrew Tupou.

Further tries to Perrett and Anasta gave the Roosters a seemingly unassailable lead but the Rabbitohs produced another of their trademark comebacks.

Five-eighth John Sutton set up a try to fullback Nathan Merritt and scored one himself, while hooker Issac Luke scampered through some fatigued defence and winger Luke Capewell crossed inside the last five minutes to set up the dramatic climax.

Sandow's potential match-tying conversion cannoned off the left-hand upright.

"The boys played with a lot of character in the whole game, we really tried hard for the 80 minutes and there was a lot of effort in everything we did," Taylor said.

"The scoreline at halftime didn't reflect the commitment that we played with.

"There was one soft try just before halftime which was disappointing, but the other tries, there was a bit of luck in them, I felt the first try should have been given no-try and there was a clear knock-on before they got to that position.

"I felt we were unlucky to be 14-0 down at halftime and then in the end we were unlucky not to get it to at least extra time."

Taylor said he didn't get a look at the possible 40-20 kick from halfback Sandow in the closing seconds, but thought as there were only about 15 seconds remaining at the time, that the Rabbitohs would have needed a "miraculous" play to win the match.

Fittler was relieved the 40-20 ruling had gone in his side's favour.

"It was hard to think at the end of the game whether I was happy or cranky but I think I was happy when he (referee Steve Lyons) called it a non 40-20,"

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