ARLINGTON, Texas -- Never in Mike McCarthy's dreams did he think his first home game as Dallas Cowboys head coach would go like this.

But he won't forget it, either.

What looked like one of the worst losses of McCarthy's career and one of the most lopsided the Cowboys have had in recent years turned into a spectacular win.

Greg Zuerlein's 46-yard field goal as time expired gave the Cowboys an exhilarating 40-39 victory over the Atlanta Falcons.

A squibbing onside kick by Zuerlein that was recovered by C.J. Goodwin and followed by a 24-yard catch by rookie CeeDee Lamb from Dak Prescott set up Zuerlein's winner.

McCarthy was surely looking at his first loss at AT&T Stadium, where he was 4-0 as coach of the Green Bay Packers, including a win against the Pittsburgh Steelers in Super Bowl XLV.

The Cowboys trailed 20-0 in the first quarter after losing three fumbles and seeing a fake punt try fail. They were down 29-10 at halftime after the defense allowed scores on six straight possessions.

They were down 39-24 with less than five minutes to play. According to ESPN Stats & Information, teams were 1,875-6 when leading by 15 or more points in the final five minutes of regulation over the past 20 seasons. The last team to overcome such a deficit was the New Orleans Saints against Washington in 2017.

It tied for the second-biggest comeback in team history. Three times the Cowboys have overcome 21-point deficits with the last coming in 2014.

For McCarthy, it also was the second-biggest comeback of his coaching career. In 2013, his Packers trailed the Cowboys by 23 and won 37-36. In Week 13 of 2015, they beat the Detroit Lions and in the 2018 season opener against the Chicago Bears, they were down 20.

To get there, the Cowboys needed some luck -- like the onside kick -- and some guts. Prescott rushed for three touchdowns and threw for 450 yards while missing two plays in the second half to get evaluated for a concussion.

They also had to overcome some questionable decision-making, like failing on a fake punt on fourth-and-5 in the fourth quarter and McCarthy's decision to go for the 2-point conversion after Prescott's third rushing touchdown with 1:49 to play.

Now it's all a footnote.

And not all wins are created equal. The Cowboys did not have either starting offensive tackle with left tackle Tyron Smith scratched because of a neck injury and La'el Collins missing his second straight game with a hip injury. They did not have starting linebacker Leighton Vander Esch, who is on injured reserve after breaking his collarbone in the opener. The defense was lit up and could not make critical stops.

But it didn't matter.

McCarthy has his first win. One he never could have imagined.