Organisers of both events sought to play down the element of competition, although the Armory admitted it had felt obliged to up its game this year, knowing a rival upstart was moving in on its turf.

"I don't see it as a problem," said Noah Horowitz, managing director of Armory, when asked about what threat Frieze posed.

"It's caused us to really react in a positive way," he said in a telephone interview.

"Competition can bring out the best in people. The fair we put on this year was our strongest edition in many years."

Around 60,000 people visited Armory in March despite a reduction in the number of participating galleries to 225 from 275 in response to criticism the show had become too big.

New York is arguably the most important city in the world for contemporary art collecting, and the global market for the finest works is booming, so perhaps there is room for two fairs in the city during the spring rather than one.

But the risk is that key galleries and buyers will gravitate towards one or the other.

For Matthew Slotover, co-founder of Frieze in London that has quickly become one of the key events in the increasingly crowded art market calendar, the element of rivalry is new.

When he and business partner Amanda Sharp launched their first Frieze Art Fair in a giant marquee in London's Regent's Park in 2003, they were alone.

"It's an odd situation for us because we're not aggressive," he told Reuters.

"In London there was nothing comparable and so it was a much more comfortable situation. The reason we are doing a fair in New York is because many significant galleries asked us to.

"I don't like talking about competitors as I don't want to bash them or praise them either."

Frieze runs from May 4-7 and will be held in a temporary snake-like tent on Randall's Island -- the location across the East River is a potential barrier to attracting the large and affluent crowds necessary to a fair's success.

Slotover admitted Frieze was the only major contemporary art fair "crazy" enough to opt for a temporary structure, but believed the sense of freshness was what people wanted.

"Art is supposed to be this surprising and challenging thing -- people like new things. People have said how important that is for them."

AUCTION RECORD

The majority of visitors to Frieze's 180 galleries are likely to be members of the public with neither the means nor inclination to buy, but who want a snapshot of the contemporary art world combined with the glamour of the venue.

But there will also be plenty of serious collectors, many of them in New York for the series of auctions at Christie's and Sotheby's held at the beginning of May each year.

"It's a key moment in New York and galleries often have their best shows on this week," Slotover explained.

"It's a logical time to do a fair. There is a cross-over between the auction and gallery market, although not a 100 percent cross-over."

He said he was hoping that the sale of Edvard Munch's masterpiece "The Scream" at Sotheby's on Wednesday night would set a positive tone for the fair opening two days later.

"If that goes for a massive sum, that puts people in a good mood for the rest of the week. I hope it does well," he said, speaking before the auction took place.

The painting in fact fetched $120 million, making it the most valuable work of art ever sold at auction.

Armory's Horowitz argued that holding a fair at the same time as the auctions was a "double-edged sword".

"There's a danger in holding a fair during auction week, as people may be looking to see prices in the secondary market before putting their money into the primary market."

It is not only New York that runs the risk of art fair fatigue -- events have cropped up around the world to tap into the growing base of collectors, including from emerging powerhouses like Russia, China and the Middle East.

"The international art fair landscape has increased exponentially," said Horowitz.

"I think there could be a thinning out among fairs and a larger concentration around the larger fairs. For the moment the amount of buyers coming to market is significantly larger than it has been before."

(Reporting by Mike Collett-White, editing by Paul Casciato)

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