It’s difficult to quantify comebacks, mainly because there’s no hard and fast rule for what constitutes a comeback victory. But Pro-Football-Reference has criteria in place. According to them, to earn a fourth-quarter comeback, you must:

Win the game (no ties or losses)
Take the field with a 1-8 pt deficit (1-7 prior to 1994) and score as an offense (no fumble return TD to win the game)
It does not have to be the final winning score (hence, that applies to the number of game-winning drives)

The guys at PFR have been keeping track of these events since the dawn of time, and thus have a comprehensive list of every quarterback and team that has come from behind to win, with a related tally of all game-winning drives.

Based on that metric, three teams have come back in the fourth quarter to win more than anyone else this year: the 49ers (seven comebacks), the Giants (six) and the Cardinals (six).

(Niners quarterback Alex Smith, Giants quarterback Eli Manning and Broncos quarterback Tim Tebow are tied with the most game-winning drives with six apiece.)

For the sake of comparison, AFC championship competitors New England and Baltimore have combined for just three comebacks this year. In total, there were 66 during the regular season, with Manning and Smith accounting for 10 (Smith had his sixth on Saturday). That’s 15 percent of the comebacks this season.

A look at the 11 comebacks orchestrated by the Giants and Niners this year:

Week 3: Giants 29, Eagles 16 — Manning throws two touchdown passes in the fourth quarter.

Week 3: 49ers 13, Bengals 8 — San Francisco trailed 3-0 at halftime and 6-3 in the fourth quarter.

Week 4: Giants 31, Cardinals 27 — Manning throws two touchdown passes in the final four minutes.

Week 4: 49ers 24, Eagles 23 — Frank Gore’s game-winning touchdown comes with three minutes left.

Week 6: 49ers 25, Lions 19 — The Niners score 10 points in the final two minutes.

Week 8: Giants 20, Dolphins 17 — Manning hits Victor Cruz with six minutes left and New York’s D holds.

Week 9: Giants 24, Patriots 20 — Manning hits Jake Ballard with 19 seconds on the clock.

Week 10: 49ers 27, Giants 20 — San Francisco outscores New York 14-7 in the fourth quarter.

Week 14: Giants 37, Cowboys 34 — New York scores 15 points in the final three minutes, 20 seconds.

Week 16: 49ers 19, Seahawks 17 — David Akers kicks a field goal with three minutes left and the D holds.

Divisional playoffs: 49ers 36, Saints 32 — Smith leads two touchdown drives in the final four minutes.

As you can see, San Francisco’s comeback victories haven’t been quite as majestic as New York’s. But the Niners are coming off of their most impressive comeback yet.

Also of note: four of Manning’s five comebacks have been on the road, while only two of Smith’s have taken place at home.

So based on what we’ve seen from these teams throughout the year, no fourth-quarter lead will be safe at Candlestick on Sunday.