NEW HAVEN, Conn. (AP)—New Haven’s professional tennis tournament is becoming a women’s-only event, with Yale University and a couple of major corporations replacing a single title sponsor.

The tournament, which had been one of just four sanctioned by both the men’s ATP Tour and the women’s WTA Tour, will be called the New Haven Open at Yale and will feature a field of 28 women, along with a doubles draw.

Yale, Yale-New Haven Hospital, Aetna and American Express have agreed to sponsor the tournament for the next three years, said Anne Worcester, the tournament’s director.

“Today’s announcement is an out-of-the-box, good-news solution to ensure that this large-scale, international sporting event will stay in our region for a minimum of three years,” Worcester said Thursday.

Pilot Pen Corp. of America had been the tournament’s main sponsor for 15 years, but ended its relationship, citing economic factors, after moving the company’s headquarters from Connecticut to Florida last year.

The tournament’s draw has traditionally suffered from its spot on the schedule. It will again be held just before the U.S. Open, August 19-27, 2011 at the Connecticut Tennis Center at Yale.

Many top players choose to take the week before a major tournament off. Others ask for a wildcard entry just before it begins because they feel they need more matches to prepare for the major. Worcester, a former chief executive of the WTA, had been able to attract top women players to New Haven, but had a more difficult time with the men.

“While we really would have liked to keep the men’s event, the financial model for staging a combined tennis tournament simply didn’t work,” she said.

New Haven Mayor John DeStefano said the tournament, with an estimated $26 million impact on the Connecticut economy, has become an important part of the area’s image as a cultural center.

“The tournament is a New Haven tradition,” he said, “that residents and visitors alike look forward to every year.”