David Warner has been effectively ruled out out of the triangular series and may require surgery for a broken left index finger suffered while fielding during Australia's victory over South Africa in St Kitts on Saturday.

In a grievous blow to Steven Smith's side, Warner will be lost to the top order for the remainder of the tournament and is now in a race to be fully fit in time for the start of the Test tour to Sri Lanka in July. He had made an unbeaten half-century and a century in three innings of the triangular series so far, following a successful IPL.

Australia's team doctor Geoffrey Verrall said Warner's recovery time could be anywhere between two and six weeks if he does not require surgery, but he may be out for longer should a procedure be required.

"The x-ray showed an intra-articular fracture of the distal phalanx of the index finger of the left hand - the top part of that finger," Verrall said. "We will assess the situation over the coming days to see if the injury requires a surgical option but should that not be the case then David is likely to be available to return to play in somewhere between two and six weeks."

The selector on duty Trevor Hohns and interim coach Justin Langer are yet to decide whether Warner will be replaced by another player flown in from Australia or elsewhere. Warner said the injury would provide him with an opportunity for downtime ahead of a demanding international schedule over the next 12 months.

"It's obviously disappointing to be sidelined given the form I've been in and given the important stage the tri-series is at, but it's always important to look at the positives," he said. "This downtime, however long or short it is, will give me the chance to freshen up and spend quality time with my family after an intense period of action."

Langer said he was particularly disappointed to lose Warner's services after watching the example he had set around the squad. "It's doubly disappointing to have David Warner sidelined because of his outstanding form plus his attitude and professionalism around the group which has been a joy to work with," he said. "But we've spoken from day one of this tour about every single person in the squad contributing to our success.

"I've encouraged the players not in the starting eleven to be ready at all times because you never know when opportunities might come. One of the boys will now get that opportunity in David's absence."

Australia's captain, Steven Smith, said that while it would be a blow for Australia to miss Warner during the tri-series, the main goal would be to ensure Warner was available for the first Test against Sri Lanka, which begins in Pallekele on July 26.

"The most important thing from my aspect is that he's right for the Test series," Smith said. "That's still about six weeks away before the first Test. I think the medical staff and Davey are confident that he'll be fine for that first Test match.

"It's always tough missing players like Davey, particularly at the moment. He's in the form of his life and batting beautifully. It's going to be a big loss for us. I'm sure whoever steps into that position is going to do a terrific job."

Warner's injury may mean a recall for Glenn Maxwell, following the allrounder's poor displays in the opening two matches of the tournament. Usman Khawaja is likely to move up the order to partner Aaron Finch for Monday's match against the West Indies.