Match delays and umbrellas could soon be a thing of the past at the US Open

US Open organisers look set to approve plans to build a $100m roof over the Arthur Ashe Stadium.

United States Tennis Association chief executive Arlen Kantarian said: "I would say at this point it's a question of when as opposed to if."

Rain halted Rafael Nadal's semi-final against Andy Murray on Saturday and postponed the women's final between Serena Williams and Jelena Jankovic.

Both singles finals will now have to be played on Monday.

It is the first time an extra day has been needed at the tournament since 1987 and it appears organisers are now ready to follow the lead of Wimbledon, where a roof is being built for next summer's championships.

"We have now completed, as of last week, our third group feasibility study," said Kantarian.

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"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 next year.

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

"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."