Ready. Set. Spend!

The NFL’s free agent frenzy began Tuesday, with several stars, including Nnamdi Asomugha, Ryan Fitzpatrick and Antoine Winfield looking for jobs after they were cut in cost-saving moves on a busy opening day of free agency.

The Baltimore Ravens are paying the price for winning a Super Bowl. The NFL champions lost two key components of their defense in Paul Kruger and Dannell Ellerbe. On Monday, they traded star receiver Anquan Boldin, a key to their title run, to San Francisco — the team the Ravens beat 34-31 to win the championship.

Kruger went north to division rival Cleveland for a five-year, $40 million deal, while Ellerbe headed south to Miami for $35 million over five years. Mike Wallace, a former Steelers star receiver, joined Ellerbe in choosing the Dolphins.

Baltimore did sign free agent defensive end Chris Canty, who spent the previous four seasons with the New York Giants.

The 49ers didn’t go untouched, either. After giving up a sixth-round draft pick for Boldin, they saw tight end Delanie Walker leave for Tennessee.

San Francisco also confirmed the trade of backup quarterback Alex Smith to Kansas City, a deal that was known for weeks. The 49ers will receive the Chiefs’ second-round pick, 34th overall, in this year’s draft and a conditional pick in next year’s draft.

The 32-year-old Boldin expressed surprise that he was traded.

“I thought this was the last stop of my career but regardless of the circumstances I came here to win a Championship ... and in February we came home Champions,” he said on Twitter.

Kruger led the Ravens with nine sacks and added 2½ in the playoffs and two in the Super Bowl. But he was too expensive for Baltimore to keep.

Denver ensured that Peyton Manning will be the Broncos’ quarterback through at least 2014.

The four-time MVP’s contract called for a guaranteed salary of $20 million in 2013 and 2014 if he was on the Denver roster Tuesday. The final two years of his contract are worth $19 million each, but are not guaranteed.

Coming off multiple neck operations, Manning threw for 4,659 yards and 37 touchdowns last season and was the NFL Comeback Player of the Year. He turns 37 on March 24.

Kansas City was busy finding support for Smith on both sides of the ball. The Chiefs agreed to a four-year, $16 million deal with tight end Anthony Fasano, a three-year, $12.6 million contract with defensive tackle Mike DeVito, and a three-year deal with Saints backup quarterback Chase Daniel.

Fitzpatrick, the Bills’ starting quarterback, was released 1½ years after getting a six-year, $59 million contract extension. Fitzpatrick struggled after signing the new deal, and the Bills went 6-10 in 2011 and in 2012.

Philadelphia released Asomugha, who two years ago got a five-year, $60 million contract with $24 million guaranteed when he left Oakland as a free agent. Asomugha was a flop in Philly, often victimized in single coverage.

Asomugha was scheduled to make $15 million next season, with $4 million guaranteed.

Earlier, Tony Gonzalez changed his mind and decided to return to the Falcons.

The NFL’s career leader among tight ends with 1,242 receptions and 103 touchdowns said he was 95 percent certain he would retire after 2012, but the other 5 percent won out.

Hours before free agency began Tuesday, Gonzalez tweeted:

“The lure of being on such a great team and organization, along with unbelievable fan support was too good to pass up.”

The Falcons also agreed to a six-year contract with left tackle Sam Baker, bringing back another key player on a team that came up just short of the Super Bowl.

Defensive end Will Smith and linebacker Jonathan Vilma, both implicated in the Saints’ bounty scandal, agreed to restructure their contracts to remain with New Orleans.