TAMPA — The promotion of a rookie into the starting lineup this early in a season is usually big news. It happened for linebacker Ryan Connelly but the Giants lost, again. Before long, the ascension of another rookie, Daniel Jones, at another position, quarterback, surfaced as the breaking news.

Connelly, a fifth-round draft pick from Wisconsin, came off the bench and played 26 of the 68 defensive snaps in the opener against the Cowboys. That was enough for the coaching staff to move him up and send opening-day starter Tae Davis to the sideline. Connelly started and played 64 of the 76 defensive snaps in a 28-14 loss to the Bills. Davis did not play a single snap on defense.

Connelly had six tackles in his starting debut and will stay in the starting lineup for Sunday’s game against the Buccaneers.

“There’s a lot of things I definitely can do better,’’ Connelly told The Post. “That’s what you prepare for. The coaches say it all the time: You’re one snap away from playing every play. If you don’t have that mindset you can definitely get caught off-guard.’’

Defensive coordinator James Bettcher made the move to start Connelly and said he “did some really nice things in the game. There are certainly things to clean up and keep growing and improving on. I’m encouraged with where he’s at, but more importantly, the direction he’s heading in.’’

With 5:53 remaining in the fourth quarter, Bills running back Frank Gore plowed over Connelly on a 1-yard touchdown run. No linebacker wants to be on the wrong end of a confrontation like that.

“I believe he’s the fourth-leading rusher in the history of the NFL, so he knows what he’s doing back there,’’ Connelly said of Gore. “I have to do a better job of getting a little lower, coming downhill a little quicker. Any time someone scores on you, you want it back. I know what I can do to get better on that. I’ll try not to let that happen again.’’

It is remarkable how opponents speak of Saquon Barkley in almost reverential terms. The Buccaneers defense held do-everything Christian McCaffrey to 37 rushing yards and 16 receiving yards last week, seemingly a good sign heading into a game against do-everything Barkley.

“Not really,’’ Bucs coach Bruce Arians said. “It’s a little bit different style of running game. I think that Saquon is one of those guys that he’s on another planet with his size, speed and also his pass catching ability. McCaffrey is a different style runner, but they are both very dangerous. I think Saquon is probably the best in the league right now.’’

The Giants liked LB Devin White from LSU, taken by Tampa Bay at No. 5 in the draft — one pick before the Giants selected Jones. White will not play in Sunday’s game because of a knee injury he sustained last week.

After practicing this past week in near-perfect temperatures, the Giants will play Sunday in sticky 90-degree conditions.

“Back to humidity,’’ said center Jon Halapio, who is from nearby St. Petersburg. “Getting spoiled with this cool weather.’’