The biggest surprise pick in Thursday's NFL draft was when the Atlanta Falcons picked quarterback Michael Penix Jr. after signing veteran Kirk Cousins to a four-year $180 million contract.

The first-round No. 8 draft pick sent social media into a tailspin and came as a shock to Cousins.

"It was a big surprise. We had no idea this was coming," Cousins’ agent, Mike McCartney, said in a text to the NFL Network. "The truth is the whole league had no idea this was coming. We got no heads up. Kirk got a call from the Falcons when they were on the clock. That was the first we heard. It never came up in any conversation."

Moments before the pick, McCartney warned in a post on X: "Bout to be shocked."

Cousins, 35, has not publicly commented on the Falcons picking Penix.

Social media quickly reacted to the shocking news.

At a news conference following the draft, head coach Raheem Morris said they felt it was important "to address our future quarterback right now while we're picking this low in these moments."

"Fortunately enough with us, we got a Kirk Cousins in the building, we got a guy that can go out there and win football games and we should be picking high enough," he added.

General Manager Terry Fontenot said that picking Penix was about the team thinking "about the future." Penix, 23, is a rookie from the University of Washington.

"These are not easy decisions. These are tough decisions," he said. "We're going to build a sustained winner and we're going to win for a long time. ... Very, very exited about Kirk. That has not changed."

In May, the Falcons signed Cousins to a 4-year, $180 million deal with $100 million guaranteed. The veteran quarterback was drafted in 2012 by Washington and spent six seasons with the team before joining the Minnesota Vikings in 2018.

This won't be the first time a high-profile, veteran quarterback will have to uncomfortably share a sideline with another signal caller seemingly destined to replace him.

Sure-fire Hall of Fame quarterback Aaron Rodgers sat on the bench for three seasons, backing up Brett Favre in Green Bay before the Packers finally went with the first-round pick from California.

Steve Young and Joe Montana shared the San Francisco 49ers sideline between 1987 and 1992 before the latter was traded to Kansas City.

Joe Flacco led Baltimore to a Super Bowl title in 2013 — but the writing was on the wall when the Ravens drafted Lamar Jackson in the first round of the 2018 draft. Jackson took over for an injured Flacco halfway through his rookie season and won the league MVP award in 2019.

This article was originally published on NBCNews.com