The Nets had grit. But Milwaukee had Giannis Antetokounmpo.

The latter won out.

The Nets lost 129-125 to the Bucks before 17,935 at Barclays Center on Monday night, not because of the Greek Freak’s offense but because of his defense when Milwaukee needed it.

After five ties in the final minutes, Antetokounmpo (36 points, 12 rebounds) not only had the dunk that gave the Bucks the lead, but the defensive stops to preserve it.

He blocked Dorian Finney-Smith with 28 seconds to play and red-hot Cam Thomas with 15 seconds left.

“We just missed the shots, honestly. It just comes down to making shots at the end,” said Thomas, who had a game-high 45 points squandered by Brooklyn. “Doe went down and missed the layup, could’ve tied the game up. But … we got [another] chance to tie. … I went to the hoop, tried to get fouled or just a bucket and Giannis contested it.”

In what is shaping up as a brutal four-game gauntlet, the Nets have lost to the Celtics and Bucks, with the Clippers (and James Harden) coming in Wednesday followed by Friday’s trip to Boston.

“That’s gonna be the standard for us,” Ben Simmons said. “This is level we want to play at. So, we’re ready to compete. Every game that we play is gonna be probably a closer game, given the guys that are out right now, the things that we’re dealing with. But we have the bodies.”

“Just keep building,” Thomas said. “It just comes down to making shots and missing shots. Sometimes we’re gonna make ’em, sometimes we’re gonna miss ’em. It’s just part of the game. Hopefully on Wednesday we make the shots and come out with the win. But at the end of the day, you just gotta keep building and learn from this, like I’m gonna learn from it.”

Damian Lillard — whom the Nets never pursued this offseason despite constant reports linking them — had 21 points, seven assists and six rebounds.

Thomas is rapidly developing into the kind of player who could change Nets GM Sean Marks’ calculus about what star to chase. The young guard has provided a great running mate for Mikal Bridges, who added 31 points, five boards and four assists.

“That’s who Cam is. The man is a certified bucket,” Bridges said. “Honestly, he’s our best scorer, and can just go get it.”

But Thomas will surely rue the two points he couldn’t get.

The game was knotted at 115, 117 and 119 with 3:02 remaining.

Thomas drove and tied it again at 121, and after a Khris Middleton bucket, Bridges pulled them even again at 123.

But after an Antetokounmpo dunk, Thomas missed a 3-point attempt.

Then on the next trip, Finney-Smith got blocked under the basket by Antetokounmpo.

Lillard had a chance to give Milwaukee breathing room but made just one of two at the free throw line, leaving Brooklyn down just three with 23.4 seconds left in regulation.

But Thomas’ layup attempt got blocked by Antetokounmpo with 15.1 seconds to play, and Milwaukee closed the game out from there.

“We got some good looks, but that’s who he is,” Bridges said. “That’s what makes it tough, because his length and him being in the conversation for [Defensive Player of the Year] every year. … So, to be on the weakside and being at the rim to cause a lot of trouble.“We’ve played those good teams but just high level, even more high-level teams like Milwaukee and Clippers and Boston. That fourth quarter just kind of gotta be, just, ‘Everybody lock in and do everything right. Help rebound, be in the right shifts.’ It’s just that fourth quarter, but I mean, learn now. It’s gotta get better.”