SANTA CLARA, Calif. — The San Francisco 49ers spoiled Aaron Rodgers’ comeback against the New York Jets on Monday by defeating the quarterback in his first game since tearing his left Achilles tendon nearly a year ago.

The reigning NFC champions opened their season with a 32-19 win over New York without star running back Christian McCaffrey, who surprisingly dropped out shortly before kickoff.

The 49ers managed to keep Rodgers and the Jets in check and dominated the time of possession from 38:40 to 21:20.

Here is the most important information for Monday evening for both teams:

On Friday, McCaffrey said he had no doubts about playing on Monday despite his calf and Achilles tendon injuries. So it was a shock when McCaffrey dropped out 90 minutes before kick-off.

But McCaffrey’s absence also presented an opportunity for backup Jordan Mason — who had never played more than 27 offensive snaps in a game — to start for the first time in his three NFL seasons. No matter, because Mason looked like a 10-year veteran, running around and getting past and over Jets defenders all night.

Once Mason’s work was done, the first look at the 2024 Niners bore a striking resemblance to San Francisco teams of recent times. After a somewhat slow start in the first quarter, the 49ers flipped the switch and physically dominated the Jets on both sides of the ball.

It was Mason who set the tone, finishing with career highs in carries (28) and yards (147). He scored a touchdown and became the sixth Niner since 1970 to record over 100 rushing yards in his first career start with the team.

The 2022 undrafted free agent from Georgia Tech was also the 10th undrafted 49er to rush for over 100 yards in a game since coach Kyle Shanahan took over in 2017, the most in the NFL during that time.

It’s unclear how many games McCaffrey will miss. With the next two games being played on artificial turf (at the Minnesota Vikings and Los Angeles Rams), the Niners won’t rush him back. Mason assured them that they won’t need to.

QB Breakdown: With the running game going well, the 49ers didn’t need much from Brock Purdy. But he still delivered when it mattered, and his performance would have been even better if it weren’t for some costly drops, including at the end of the first half when wideout Brandon Aiyuk dropped a potential touchdown. Purdy finished the game completing 19 of 29 passes for 231 yards with no touchdowns or interceptions.

Promising trend: The 49ers’ run defense struggled in 2023, allowing 4.8 yards per carry from Week 14 through the Super Bowl (30th in the NFL). They tried to correct that in the offseason by hiring Nick Sorensen as defensive coordinator and dedicating resources to more big players on the defensive line such as tackles Maliek Collins and Jordan Elliott and end Leonard Floyd.

Maybe it’s too early to call it a trend, but early results on Monday were good, as San Francisco limited the Jets to 68 yards on 19 attempts, an average of 3.6 yards per attempt.

Decisive game: With 8:56 left in the second quarter, the Niners trailed 13-6 and were forced to face a second-and-19 attempt at New York’s 39-yard line after a holding offense nullified an 18-yard run by Mason.

Purdy had an open pocket and time to throw and threw the ball to wide receiver Jauan Jennings, who ran a deep crosser. Jennings caught the ball for a gain of 22 and a first down. The Niners scored three plays later and never relinquished the lead. — Nick Waggoner

Next game: at Minnesota Vikings (1:00 p.m. ET, Sunday)

It took a year longer than expected, but the Jets finally got to see Rodgers play for nearly a full game. Unfortunately, their defense was not up to the task and prevented any chance of a triumphant return from Rodgers. The Jets briefly led 7-3, but then allowed eight – yes, eight – consecutive scoring drives.

After his great performance, the Jets made Mason from the 49ers the hottest new name in the country for fantasy owners.

One of the reasons Rodgers wanted to play for the Jets was their impressive defense, which helped them survive most games last season despite suffering from quarterback roulette.

However, that game slipped away from them and coach Robert Saleh waved the white flag with 4:32 left and took Rodgers off the field in favor of Tyrod Taylor. And Rodgers still hasn’t played a full game in a Jets jersey.

Biggest gap in the schedule: Wide receiver Garrett Wilson was in top form at the start, catching four balls in the first 11 minutes. Then he disappeared. He was not targeted again until the third quarter, and that led to an interception. The connection between Rodgers and Wilson stalled, and with it the entire offense.

The lack of a consistent No. 2 in the passing game has been a major problem. Wideout Allen Lazard’s 26-yard pass reception late in the third quarter was the first offensive touch by a player other than Wilson or running back Breece Hall. Wide receiver Mike Williams, in his first game since his ACL surgery, played only a few snaps and was a non-factor. Tight end Tyler Conklin had no targets. If this becomes a weekly trend, calls for a trade for wideout Davante Adams from the Las Vegas Raiders will become louder.

Worrying trend: The Jets’ defensive front, the supposed strength of the unit, was pressured in the run game. They were obviously missing strong-side end John Franklin-Myers (traded in the offseason). Big defensive tackle Javon Kinlaw should have been the difference, but he had a quiet night. Overall, they allowed 180 yards rushing, most of it between the tackles. Holdout Haason Reddick probably wouldn’t have helped the run defense, but he would have added some spice to the lukewarm pass rush.

Worrying trend, part II: Curiously, All-Pro cornerback Sauce Gardner was benched for nine snaps in the second quarter. There was no medical issue, ESPN’s Lisa Salters reported during the game. His absence was costly, as Brock Purdy completed 6 of 6 passes without Gardner on the field. – Rich Cimini

Next game: at the Tennessee Titans (1:00 p.m. ET, Sunday)