(Photo by Kevin C. Cox/Getty Images)

In the NBA, a No. 8 seed has upset a No. 1 seed in only five of the 60 1-vs.-8 playoff series since 1984. But this year it could happen twice, which is odd because the top seed in the NBA falls in the first round less frequently than any of the four major sports.

The No. 8 Hawks are up on the top-seeded Pacers, 3-2, in the East while the No. 8 Mavericks are tied at two games apiece with the No. 1 Spurs in the West, and three-pointers have played a huge key in these two series and in past 8-1 upsets.

In 2007, the Warriors made 10.3 three-pointers per game in their series win over the top-seeded Mavericks. This postseason, no team has been more reliant on the three-pointer than the Hawks, who have averaged 11.8 three-pointers per game. On Monday, Atlanta set a franchise playoff record with 15 three-pointers, including nine in a 41-point second quarter. Mike Scott was 5 of 5 from three-point range in the second quarter alone.

In 2011, it was the Grizzlies’ defense of the three-pointer that led to their first-round upset of the top-seeded Spurs. San Antonio shot an NBA-high 39.7 percent from three-point range during the regular season that season, but Memphis held the Spurs to just 29.4 percent from behind the arc in their series.

Three years later, the Spurs are just as reliant on the three-pointer. Once again, they led the NBA in three-point field goal percentage, connecting on 39.7 percent — the exact same rate as 2010-11.

During the regular season, the Spurs averaged 8.5 three-pointers per game, but in its first four games against the Mavericks, San Antonio has averaged just six three-pointers — 13th most in the playoffs — and is shooting 31.6 percent from beyond the arc.

The three-point line is basketball’s equalizer. If the Hawks and Mavericks are going to become the latest No. 8 seeds to beat a No. 1, they’ll need to win their three-point battle.