'I would say at this point it's a question of when as opposed to if,' Arlen Kantarian, the United States Tennis Association's chief for professional tennis, told reporters after tropical storms washed out the second men's semi-final and women's final on Saturday.

'We have now completed, as of last week, our third group feasibility study.

'We are a lot more optimistic, given the new technology, given the lighter weight and translucent technology that is available today.

'Our board has approved taking this concept to a more serious construction-planning stage, cost estimates, and we're in a position, unlike three years ago, where we feel this tournament would require a roof.'

Of the four grand slam events, the Australian Open has two courts with a roof, while Wimbledon's Centre Court will have a new translucent retractable roof in 2009.

The issue came to a head on day 13 of the hardcourt major after the completion of the men's second semi-final between Rafael Nadal and Andy Murray was postponed until Sunday because of rain.

The final will now be played a day later than planned, on Monday, the first time since 1987 that the tournament has required an extra day.

'I will tell you that it is on one hand somewhat pretty hard to justify spending somewhere in the region ofUS $100 million when you have had (only) nine cancelled sessions in the last 20 years of a tournament,' Kantarian said.

'That being said, we believe this tournament has now reached a point, given the growth of the tournament, the number of fans, the number of countries that it is televised in, where we have to look seriously, regardless of that data, at putting a roof over Arthur Ashe (Stadium) to protect this kind of thing from happening.' -- REUTERS