Eli Manning is 35 years old. At some point he’s going to go into one of these slumps that have dogged him throughout his career and not come out of it. It will be, once looked back on, the beginning of the end. The start of the final slide. Time, as they say, is undefeated, which is more than we can say about the Giants these past three weeks.

But the receiver who knows Manning the best in the Giants’ locker room is convinced that is not what we have seen these last few weeks.

“Not true,” Victor Cruz said Wednesday to speculation that the quarterback is starting to decline for good. “No one is hitting the panic button on Eli Manning.”

Cruz, having just finished convincing the football world that his own career was not over after knee and calf surgeries kept him off the field for almost two full years, is now heading the cause that Manning still has a few good years left in him. Or maybe even decades.

“I’m convinced he’s playing until he’s 55 years old, at least in my mind,” Cruz said, clearly unwilling to face a future whether near or distant without Manning. “He knows. He knows his body better than anyone in this league, better than any doctor or anyone can tell him. When he knows, when the time comes, I’m sure he’ll handle it accordingly.”

This, Cruz insists, is not that time.

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That confidence does not dismiss the urgency the Giants feel to get Manning and the entire offense back to playing well. They have scored only two touchdowns in the last 10 quarters, had their worst passing production in more than two seasons Sunday against the Packers, and have yet to show anything beyond the quickest flashes of what their offense is supposed to be capable of producing. They get another chance Sunday against the Ravens at MetLife Stadium.

In the past two games, Manning’s longest completion to any of his wide receivers — Cruz, Odell Beckham Jr. and Sterling Shepard — has gone for just 16 yards. Cruz didn’t have a reception Sunday for the first time since 2011, something he called “unfortunate.”

“Obviously, he knows within himself what he has to fix and change,” Cruz said. “We understand that he’s our quarterback and he’s still playing in great form. You can’t just go off a couple of games and negate what he has done in the games that we won and the good things he’s done. It’s easy to harp on the negative things, but we have to look at the positives as well.”

Beckham, too, defended Manning from his critics.

“When you lose, everyone wants to point the finger somewhere,” Beckham said. “Things have to be written, things have to be said, and that’s just how it is whether it’s the truth or not the truth. That’s just the way this world works. You win, and it’s like nothing ever happened.”

The Giants have to get to that point of winning, though, to convince some that Manning’s career has not peaked and is not on the downhill side of his two Super Bowl MVP awards.

“It’s not the level of football that we want,” Cruz said of the offensive performances through the first five games. “Everyone is committed to turning this thing around and making sure that our next game we put our best foot forward and we play Giants football.”

Cruz then reiterated the mantra that many on the Giants have been espousing for the past two weeks, that the offense is close and ready for a breakout.

“I truly feel like we’re on the brink and we just have to put it together for one of those games and be consistent from there,” Cruz said.

Whether Manning has any of those games left in him will be up for debate, at least until he does it.