New Sri Lanka captain Kusal Mendis vowed Sunday to conquer the "personal weakness" which saw him hospitalised at the Cricket World Cup.

Mendis is his country's marathon man, making 76 and 122 in the two defeats to South Africa and Pakistan.

The 28-year-old is also the team's wicketkeeper and now is the captain after injury sidelined Dusan Shanaka for the rest of the tournament.

Mendis's exertions have taken their toll, needing hospital treatment after cramping during his lengthy stint at the crease before Pakistan chased down 344 to beat them in Hyderabad last week.

"The intense heat during every match here has been a challenge. I genuinely regret experiencing cramps after my batting," Mendis said Sunday.

"I believe that had I been able to field, we might have achieved more. It's a personal weakness I didn't anticipate.

"I think it was a result of overexertion. I'll take measures to ensure it doesn't happen in the future."

Mendis will be playing in his 115th ODI against Australia on Monday as both teams seek their first win of the tournament.

Sri Lanka have had no problems scoring runs -- 326 against South Africa and 344 in the game with Pakistan.

Unfortunately for the 1996 champions, they conceded a World Cup record 428 to the Proteas while Pakistan's pursuit to win by six wickets was the highest successful chase in tournament history.

"Australia has lost two matches, and we've also faced two losses in our recent games," added Mendis.

"I consider this a positive situation. When we take into account the two defeats we had, we're performing at a commendable level.

"I think we are better than them as a batting unit."