Twenty million Sri Lankans will be scrutinising Muttiah Muralitharan's medical bulletins for the next few days after the world's most prolific bowler was stricken by a hamstring problem during his team's victory over New Zealand on Friday.

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The wily off-spinner battled through the pain barrier to pick up four wickets to propel Sri Lanka to a thumping 112-run win in their final Group A match but his injury caused a few headaches for captain Kumar Sangakkara and millions of their supporters back home.

"I dived and got injured a little bit. I strained a hamstring. It's not a big tear, maybe a small one, but it was a discomfort," said the 38-year-old, whose trademark smile gave no hint of the pain he was going through.

A fully fit Muralitharan can terrorise most batsmen on most pitches -- as vindicated by his haul of 1343 international wickets.

On the slow and low pitches of the sub-continent, he is even more potent and the 1996 champions simply cannot afford to lose his services at this stage of the competition as they look to become the first Asian side to win the trophy twice.

His captain knows this well and was keeping his fingers crossed that the injury did not rule out cricket's most prolific bowler from the knockout stages.

"We've got a few days... hopefully he can be fully fit within that time period," said Sangakkara.

"We've had guys with injuries before and we managed to fix them up pretty quickly. Hopefully we will have him again for the quarter-finals.

"He needs to play. This is his last World Cup. We enjoy playing with him, he wins a lot of matches for us. What he does really well is bowl and take wickets so we just want him to do that."

That is exactly what he did on Friday.

He made life miserable for the New Zealand batsmen after Sangakkara (111) scored his maiden World Cup century to rescue his team after some early jitters to set a 266-run target.

- World Cup coverage

The off-spinner, playing his last international tournament, showed off his full repertoire in front of the 23,000-odd crowd at Wankhede Stadium, the venue for the April 2 final, and ensured that the Kiwis never got a footing to launch a reply.

On a track that offered a bit of spin, he mixed his sharp off-spinners with the occasional doosras and the New Zealand batsmen never came to terms with his line and length.

"I'm bowling well. The dew factor was there, I wanted to bowl a little bit slower, off the wicket it skidded," said Muralitharan, who left the field twice to get treatment on his hamstring.

"It's hard for spinners to spin the ball but you can bowl line and length and a few doosras and you can take some wickets."

It was not just Sri Lanka who left the Wankhede Stadium on Friday with injury woes.

New Zealand suffered another scare as fast bowler Hamish Bennett limped off the field after spraining his left ankle during his delivery stride at the start of his fifth over.

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He returned to bat during the New Zealand innings, despite suffering a calf strain, with Kane Williamson as his runner.

The Kiwis are already without regular captain and frontline spinner Daniel Vettori and paceman Kyle Mills, who are recovering from injuries to get fit for the knockout stages.

"They're improving every day which is a good sign. Hamish Bennett going down today puts another spanner in the works but hopefully they'll come right in the next couple of days," stand-in captain Ross Taylor said.

Both teams had made it to the quarter finals before Friday but the win catapulted the co-hosts, who were playing away from home for the first time in the tournament, to the top of Group A.

But their final position will be determined only after Saturday's match between Australia and Pakistan.