"He'd be by $4 million a year the highest-paid relief pitcher," Yankees senior vice president Hank Steinbrenner said Tuesday. "To say that's a strong offer would be an understatement."

On Monday, the Yankees retained catcher Jorge Posada when they upped their offer to $52.4 million for four years. Posada is due to take a physical Wednesday, another step toward finalizing that agreement.

Rivera, the next step in the team's offseason plan, was allowed to start discussing money with other teams Tuesday. Steinbrenner confirmed the $45 million offer, which was made several days ago and was first reported by The New York Times.

"The ball's in their court," Steinbrenner said. "If they still want to look for more somewhere else, that's up to them."

Rivera's agent, Fernando Cuza, did not return telephone messages.

Mets closer Billy Wagner is the highest-paid reliever, averaging $10.75 million during his $43 million, four-year contract. Only four pitchers are signed for next year at higher average salaries than the Yankees' proposal to Rivera: Carlos Zambrano ($18.3 million), Barry Zito ($18 million), Jason Schmidt ($15.7 million) and Atlanta's Mike Hampton ($15.1 million).

In addition, the Yankees have a standing $16 million offer to Andy Pettitte, who hasn't decided whether to pitch or retire.

Yankees general manager Brian Cashman was more guarded in his comments about Rivera than Steinbrenner was.

"He's a free agent and he's fielding offers from other clubs. He's certainly received offers from us," Cashman said.

Posada decided not to test the free-agent market and accepted a deal averaging $13.1 million, the most for a catcher in baseball history. Before Monday, the Yankees had offered a three-year contract to the 36-year-old catcher.

Steinbrenner wasn't concerned that Posada will be 40 when the deal expires.