Alastair Cook has admitted that his England side will have to improve quickly in one-day internationals over the next few months as they look to boost their chances heading into next year's World Cup.

England face Sri Lanka in the first of seven ODIs in Colombo on Wednesday, and Cook is hopeful that his team will find their form quickly with the white ball after struggling in the shorter format earlier in the year.

"We will have to concentrate on our cricket," the England skipper told reporters. "We have this chunk of one-day cricket, which certainly I've never had - six months of it leading up to the World Cup.

"I hope we can make some really big improvements in a short space of time.

"I think we've made some really good progress in this week-and-a-half. We've talked a good game so far in meetings and nets, and I could not ask the lads for any more effort. But the crux of the matter is how we pull up on Wednesday, and how we play."

England will meet Australia and India in a triangular series in the winter before starting their World Cup campaign in February.