In a swift maneuver surprised much of the publishing industry, Knapp Communication Corp. yesterday wrested away from Texas Monthly the rights to purchase long-floundering New West magazine.

It is expected that Knapp, which publishes Architectural Digest and Bon Apetit, will complete the $4.5 million purchase within 10 days.

New West, which is published by Rupert Murdoch's New York Magazine Co., has been up for sale for almost two years, ever since the magazine began losing about $100,000 a month.

Murdoch took control of the magazine from editor Clay Felker, after a fiery battle in 1977. The sale guaranteed Felker first refusal rights on the future sale of New York, New West and the Village Voice, all of which were sold to Murdoch in a package. Two years ago Murdoch began shopping the package around to prospective buyers, reportedly offering the three for $40 million. Two publishing firms -- Gannett and Harte-Hanks -- considered the offer but decided against acquisition.

The publishing industry gossip was that Murdoch would fold New West by the end of July if he was unable to find a buyer. It was simply losing too much money. Last Friday Michael Levy, the president of Texas Monthly Mediatex Communications Corp., agreed in principle to buy New West and turn it from a biweekly into a monthly. Levy -- and most of the publishing industry -- thought the deal was then a fait accompli.

Although Felker had refusal rights and could have matched Levy's offer, it seemed unlikely that Felker would leave his just-created position as editor of The New York Daily News' new afternoon edition -- a position that would put him up against New York Post publisher and arch-rival Murdoch on a day-to-day basis.

What few seemed to realize was that Felker also had the right to sign his option over to a third party. Yesterday he did just that, granting New West associate publisher T. Swift Lockard the right to purchase New West. Sources said yesterday that Knapp Communications President Cleon Knapp had agreed to provide the $4.5 million for the purchase.

A spokesman for Levy said last night that if Texas Monthly failed to acquire New West, it would "seriously attempt" to start its own magazine in California.