Zack Wheeler has reached an agreement on a three-year, $126 million extension with the Philadelphia Phillies, according to sources, bypassing the possibility that the ace pitcher will become a free agent in the fall.

An announcement by the Phillies is expected Monday.

With a salary of $42 million, Wheeler's deal is the most lucrative extension in baseball history in terms of average annual value. It also falls in the same neighborhood of the richest salaries for pitchers; Max Scherzer and Justin Verlander signed multi-year deals as free agents with the New York Mets that averaged $43.3 million.

Wheeler, who is entering the final season of a five-year, $118 million contract, has had great success with the Phillies, a team that has doled out big money for stars in recent seasons -- Bryce Harper, Trea Turner, Aaron Nola and others. There has been a sense this spring that the right-hander and the team would work out another deal.

Wheeler's deal does not contain a formal no-trade clause, but he will soon earn what is known as 10-and-5 rights -- he has more than 10 years of service time already, and once he completes his fifth season with the Phillies, he can veto any trade.

Not that the Phillies would consider trading Wheeler, who has a 3.06 ERA in his first four seasons with Philadelphia -- with an Adjusted ERA+ of 137 -- and has 675 strikeouts in 629 1/3 innings. Wheeler also led the major leagues in innings pitched (213 1/3) in 2021 and won a Gold Glove Award last year.

Early in Wheeler's tenure with Philadelphia, owner John Middleton rejected the notion that the Phillies would ever consider trading the right-hander, saying he wouldn't deal him for Babe Ruth or Ted Williams. The front of the Phillies' rotation appears set for years to come, with Wheeler and Nola now under contract in long-term deals, and with Ranger Suarez emerging as a high-end No. 3 starter.

Wheeler, 34, was the sixth overall pick in the draft in 2009, selected by the San Francisco Giants, and as he ascended among the best prospects in the game, he was coveted by other teams. The Giants, making a push for the postseason in 2011, traded him to the Mets for Carlos Beltran.

Wheeler pitched in five seasons for the Mets, missing the 2015 and 2016 seasons after tearing an elbow ligament and undergoing an elbow reconstruction.