No. 1 seed Gonzaga almost went down to the wire with No. 16 Southern on Thursday, pulling away late for a 64-58 victory in what was a tie game with four minutes remaining.

It had us wondering how close a No. 16 seed has ever come to defeating a No. 1. Per Wiki:

Two 16-seeds have come within one point of upsetting a #1 seed, both in 1989. In the East Regional, Georgetown hung on to win 50-49 against a Princeton squad who were 30 point underdogs. Princeton had the opportunity to win the game with the last shot, but Alonzo Mourning blocked the last two attempts to secure the victory. In the Southeast Regional, Oklahoma fought back from a first-half 17-point deficit to take the lead over East Tennessee State with 1:21 remaining. ETSU also had a chance at a last-second win, but Alvin West's shot from halfcourt was deflected and Oklahoma defeated ETSU 72-71.[1] Sixteenth-seeded Murray State took top seeded Michigan State to overtime in 1990, but eventually lost 75-71. In 1996, Western Carolina missed a three-pointer to win and a two-pointer to tie in the final seconds, losing 73-71 to Purdue.

In other words, pretty close -- much closer than Southern. That said, it's been a while since a No. 16 seed got that close. Per Doc Sports:

Last year's seven-point loss to Syracuse by UNC Asheville was the first single-digit margin since 1997.

So yeah, Gonzaga was the closest to losing, at least in terms of margin, in at least 16 years. If you have Gonzaga going to the Final Four, you should probably be nervous.