Sri Lanka spinner Maheesh Theekshana has not recovered from a hamstring tear and will miss their ICC ODI World Cup opener against South Africa on Saturday, coach Chris Silverwood said on the eve of the contest in New Delhi.

The wily off-spinner sustained the injury last month, which kept him out of the Asia Cup final in which Sri Lanka suffered a 10-wicket thrashing at the hands of India.

"Theekshana is still recovering from a hamstring injury, so he won't be available for this game," Silverwood told reporters on Friday.

"But we expect him to be available very soon. The rest of them are fine."

Sri Lanka arrived with a depleted bowling unit having already lost the services of fast bowler Dushmantha Chameera and spin rounder Wanindu Hasaranga through injuries.

Dunith Wellalage will be expected to fill the void created by Hasaranga's absence and Silverwood had no doubt the 20-year-old would live up to the expectations.

"Dunith has shown us what a good young cricketer he is and he's got an old head on young shoulders," the former England coach said.

"I think he's shown his worth with bat and ball and he's a good young fielder as well."

"I want him to go out and enjoy himself and show the rest of the world how good he is and if we can do that and give him that freedom, I think we'll see the best of him."

While Sri Lanka will bank on their spinners to make the most out of what they expect to be spin-friendly conditions in Delhi, South Africa captain Temba Bavuma said pace remained their strength.

"We always kind of lean to planning around our fast bowlers. That is our strength as a South African team," Bavuma said even though he did not rule out playing both spinners -- Keshav Maharaj and Tabraiz Shamsi -- whenever conditions demand.

"When we have guys like Keshav and Shamsi, that does give us our opportunity ... to play more than one spinner."