Ryan Fitzpatrick knew.
As soon as his pass intended for receiver DeSean Jackson was picked off by Giants safety Curtis Riley in the end zone with 9:42 remaining in the third quarter and with Fitzpatrick’s Buccaneers trailing by two touchdowns, the veteran quarterback of 14 NFL seasons knew he was done for the day.
It was the third interception Fitzpatrick threw in a 38-35 Giants win Sunday at MetLife Stadium and it was a bad one — a careless throw Jets fans vividly recall him heaving on occasion when he played for them in 2015-16.
“After the third one in the end zone there, I thought that would probably be the [coach’s] decision,’’ Fitzpatrick said.
Indeed, with 6:58 remaining in the third quarter Buccaneers coach Dirk Koetter replaced Fitzpatrick with Jameis Winston, the former No. 1 overall draft pick who once was thought to be Tampa Bay’s franchise quarterback.
Winston, leading the Tampa Bay offense to four touchdowns on 12-of-16 passing for 199 yards, 2 TDs and one INT, brought the Bucs back from a 24-7 deficit to nearly stealing the game.
Koetter, of course, was noncommittal about who his starter will be next week, saying, “We’ll see. I’ll let you guys know [Monday].’’
But Fitzpatrick, who’s been the most recent beneficiary of the Buccaneers’ musical quarterback game this season, knows what the answer will be Monday.
“I’ve been in a lot of crazy situations before,’’ he told The Post. “I’ve been on the good side of them and I’ve been on the bad side of them. This year will just be another chapter for my book.’’
Fitzpatrick was at the center of several plays that led to the Giants’ win.
The first was a failed quarterback sneak on fourth-and-1 from the Giants’ 5-yard line in the first quarter. The Giants turned that into a 95-yard scoring drive to take a 14-0 lead.
Fitzpatrick later tried to force a pass over the middle to tight end O.J. Howard, and Giants safety Michael Thomas picked the ball off with 23 seconds remaining in the first half.
“I kind of forced one in there,” Fitzpatrick said. “Sometimes you make that throw hoping they don’t turn around. [Thomas] turned round and made the play.’’
On the Bucs’ first possession of the second half, a Fitzpatrick pass intended for Jackson bounced off the chest of Giants cornerback Janoris Jenkins and into the arms of linebacker Alec Ogletree, who returned it 15 yards for a TD and a 21-7 lead.
Then came the ball intended for Jackson in the end zone, intercepted by Riley.
“I just threw it up,’’ Fitzpatrick said. “[Jackson] is either going to make a play or [the Giants] were. When you throw 50-50 balls, 50 percent of the time they get it.’’
Jets fans will forever remember the magical season Fitzpatrick had in 2015, leading them to a 10-5 record with 29 TDs and just 12 INTs entering the season finale against the Bills in a game the Jets had to win to get into the playoffs for the first time since 2010.
Fitzpatrick threw three debilitating INTs that day in a 22-17 loss to Buffalo, which eliminated the Jets from playoff contention.
“I have a lot of great memories in this stadium,” Fitzpatrick said. “It was neat to be back.”
Though Fitzpatrick has had more than nine lives in his career, this almost certainly was his final chapter at MetLife Stadium.