It was a bittersweet moment for the 1972 Dolphins a year ago when the last undefeated teams of 2019 — New England and San Francisco — lost their ninth games.

Yes, the annual champagne-popping tradition continued for the living members of the only team in NFL history to finish undefeated and untied. But missing was the group’s on-field leader, Nick Buoniconti, who on July 30, 2019, was the 14th member of that great team to die.

This year, the champagne corks are waiting on only Pittsburgh (9-0) to lose before they can be fired in the 48th year since that 17-0 season. And if that time does arrive, there will be some more melancholy moments. It would be the first celebration without the group’s legendary coach — Hall of Famer Don Shula, the NFL coach with the most wins, who died on May 4 at age 90.

Perhaps it would be fitting for the streak to end with Shula’s passing.

Facing Jacksonville (1-8) on Sunday, it’s a good bet the Steelers become the league’s first team to reach 10-0 since 2015, when the Panthers started 14-0.

After Sunday, Pittsburgh faces six teams that currently have a combined record of 29-25-1. That includes four teams with winning records — Baltimore (6-3), Buffalo (7-3), Indianapolis (6-3) and Cleveland (6-3).

In 100 completed seasons, the NFL has had five teams finish without a loss. But the first four unbeaten league champions — the 1920 Akron Pros (8-0-3), the 1922 and 1923 Canton Bulldogs (10-0-2 and 11-0-1) and the 1929 Packers (12-0-1) — had ties.

Twenty NFL teams have started 10-0 or better, including the 1975 Vikings (10-0). Three teams — the 1934 Bears (13-0), 1942 Bears (11-0) and 2007 Patriots (18-0) — were unbeaten and untied before losing the championship game.

If the 2020 Steelers do make it to 16-0, they’ll still be facing one of the stronger playoff fields in memory. Heading into this week, the AFC had nine teams with records of 6-3 or better.

Steelers coach Mike Tomlin has done his best to downplay the chatter about going undefeated. Naturally, he doesn’t want his players looking past even a Jaguars team that’s lost eight straight.

“The only thing that’s perfect about our team,” Tomlin said this week, “is our record.”