In the opinion of co-owner John Mara, the Giants have made “a very substantial offer’’ to Victor Cruz, an offer Mara believes should be enough to keep the popular, salsa-dancing, Jersey-born receiver with the Giants for many years to come.

“Let’s just say if he took our offer he’d be a very wealthy young man,’’ Mara said yesterday at an NFL/General Electric press conference to announce a $40 million contribution to concussion-prevention research.

Let’s just say Cruz is angling to become wealthier than the Giants at present are willing to make him. The Giants yesterday did the expected when they placed a first-round tender on Cruz, a restricted free agent, meaning he will make $2.879 million for the 2013 season if he doesn’t come to a long-term agreement with the Giants or another team. Today, Cruz hits the open market and he wants to see if there’s anyone out there willing to make a more substantial offer than the Giants already have. If so, the Giants get five days to match the offer sheet and keep Cruz or else lose him and receive a first-round draft pick as compensation.

This high-stakes game, Mara admits, is a gamble.

“Certainly we’re taking a risk,’’ Mara said. “He is an exciting, dynamic player. It’s not going to shock me if somebody makes him an offer.”

Well, history says it would be shocking if Cruz, 26, gets an offer, as the market for restricted free agents with first-round tenders has been nil for nearly a decade. In fact, none of them has received an offer sheet since 2003. That doesn’t mean it can’t happen with Cruz, a native of Paterson, N.J., who wants to stay but also wants to get paid.