It happened on January 7, 2001 late in the second quarter of the 20-10 NFC Divisional Playoff victory over the Philadelphia Eagles at Giants Stadium.
From Ashley McGeachy of the Philadelphia Inquirer, January 08, 2001:
With the Eagles driving just after the two-minute warning, Sehorn dove in front of a pass from McNabb intended for Torrance Small. Lying on his back, Sehorn punched the ball upward, rolled to his knees, then to his feet, grabbed the ball, and sprinted 32 yards along the left sideline into the end zone.
Andy Reid asked that the play be reviewed, but the officials upheld the ruling, giving the Giants a 17-0 lead with 1:40 left in the first half.
"My natural reaction was to pop it up and hit it again," said Sehorn, who also made four tackles. "I saw how high it went, so I got up and just took it, and ran, and got lucky. . . . It was one of those do-something plays."