Baseball players ended decades of opposition to mandatory drug testing Wednesday by agreeing to be checked for illegal steroids starting next year.

Under the players' proposal, which addresses one of the key issues in contract talks, players would be subjected to one or more unannounced tests in 2003 to determine the level of steroid use. If the survey showed little use, a second round of tests would be set up in 2004 to verify the results.

If more than 5 percent of the tests were positive in either survey, players would be randomly tested for two years.

The union did not say what penalties, if any, would be levied against players who test positive.

"We had an obligation to bargain on it. It was a serious issue," union head Donald Fehr said. "It took a lot of time and effort and thought."

Rob Manfred, the owners' top labor lawyer, characterized the proposal as "very significant."

"It is the kind of proposal that will put us very easily on the path to a very timely agreement," he said.

He said a counterproposal could be ready as early as Thursday. The plan the owners put forth in February called for players to be tested three times a year for steroids and other performance-enhancing drugs, and once a year for illegal drugs.

Former MVPs Jose Canseco and Ken Caminiti admitted steroid use earlier this year, and Canseco estimated that up to 85 percent of all major leaguers took muscle-enhancing drugs during the years he played, 1985 to 2001.

"As players, we want to be able to clear our name from what Caminiti and Canseco said," Toronto's Vernon Wells said. "Unfortunately, we have to prove our innocence. If none of that happened we wouldn't have to do this."

The NFL and NBA test players for steroids and illegal drugs. The NHL has a policy similar to baseball's, testing players only if there is cause.

Both sides also discussed minimum salary, benefits and debt control.

The union's executive board is to meet Monday in Chicago and could set a strike date for what would be baseball's ninth work stoppage since 1972.

Players fear that without a contract to replace the deal that expired Nov. 7, owners would change work rules or lock them out after the World Series.