Afghanistan captain Hashmatullah Shahidi has insisted his side's World Cup wins have been the product of sustained effort, however much they have surprised the rest of the global cricket community.

Shahidi's men have produced two of the standout displays of the 10-team tournament in India, thrashing reigning champions England by 69 runs and defeating 1992 title-winners Pakistan by eight wickets last time out in Chennai.

Now, following a week's break, they will go in search of a third win over a World Cup champion when they take on 1996 winners Sri Lanka in Pune on Monday.

Afghanistan's defeats of England and Pakistan have, unsurprisingly, been labelled "upsets" and "shocks".

But Shahidi said they had not come out of the blue for an Afghanistan side coached by former England batsman Jonathan Trott.

"This team, it's not started from the World Cup," he told a pre-match press conference in Pune on Sunday.

"We were working on this team for the last two years and we had series against teams like Pakistan, Sri Lanka, Bangladesh consistently."

The 28-year-old batsman added: "We were playing a lot of domestic 50 overs cricket and we stick with our plan; we stick with the same team. When we were not doing good, we still had a belief in this team and these players. We gave them a lot of chances.

"In our good times and in our bad times, we believed in this team. That's the reason I think we are playing good cricket in the World Cup."

Sri Lanka, who've also won two of their opening five games, come into Monday's match on the back of thrashing England by eight wickets.

They are familiar opponents for Afghanistan, with several players having appeared in the Lankan Premier League.

"Keep that LPL aside, we've also played a lot of ODIs (one-day internationals) against each other," said Shahidi.

"We all know about them and they know all about us."

Sri Lanka's push for a semi-final berth, however, has taken another turn with in-form quick Lahiru Kumara ruled out for the rest of the tournament.

Kumara hurt his left thigh during training at MCA International Stadium on Monday and has been replaced in the squad by fellow pacer Dushmantha Chameera.

Chameera's inclusion was approved by the Event Technical Committee on Sunday and the experienced right-armer could come into contention to replace Kumara for that pivotal match against Afghanistan.

While Chameera has plenty of experience for Sri Lanka with more than 100 appearances for his country, the loss of Kumara will be felt after he played a huge part in their upset victory over England in Bengaluru on Thursday.

Kumara picked up the key wickets of England skipper Jos Buttler and all-rounders Ben Stokes and Liam Livingstone during Sri Lanka's eight-wicket triumph and has collected five scalps for his country through four appearances at the tournament.

Chameera's addition means Sri Lanka have now added a total of three members into their 15-player squad since the start of the tournament, with Chamika Karunaratne and Angelo Mathews having already found a way into the group following the loss of skipper Dasun Shanaka (quad) and Matheesha Pathirana (shoulder) previously.

Sri Lanka currently have two wins from five appearances at the World Cup and sit in fifth place on the standings with four group matches remaining.

Sri Lanka squad: Kusal Mendis (c), Kusal Perera, Pathum Nissanka, Dushmantha Chameera, Dimuth Karunaratne, Sadeera Samarawickrama, Charith Asalanka, Dhananjaya de Silva, Maheesh Theekshana, Dunith Wellalage, Kasun Rajitha, Angelo Mathews, Dilshan Madushanka, Dushan Hemantha, Chamika Karunaratne.