It's an amazing thing - momentum.

Round 12 of the 2017 Monster Energy Supercross season heads into Detroit on Saturday with some of the closest racing in recent memory. But in the 450 class Ryan Dungey looks vulnerable despite holding a larger point margin than what Zach Osborne has in the 250SX East class. That's because Osborne doesn't have Eli Tomac behind him ripping off wins and shedding points.

Tomac won last week in Indianapolis marking a career first three-straight checkers. He's got six wins on the season compared to Dungey's two. Regardless, Dungey holds a 12 point lead - a solid distance for someone who has yet to finish below fourth-place and with six rounds left in the season. But the bleeding started in Round 4 when Tomac entered Phoenix in fifth-place 25 points out of first-place and grabbed two straight wins.

Tomac flopped in Arlington giving Dungey a temporary respite but has since closed a 29 point deficit after that Round 6 to what now looks like an easy 12. The "What's Wrong with Dungey" chatter got more fuel this week when the two-time defending Champion said "it's just a dirt bike race, there are bigger things in life" after taking third.

Ryan Dungey has four podiums in four of the last five rounds but Eli Tomac has four wins in the last five rounds

It's a true statement. But it's also true that it appears Dungey's grip on a third-straight Supercross title and fourth overall is slipping. Or maybe it's just a clever rope-a-dope tactic that eventually serves to further cement Dungey's name in Supercross history. Time will tell. But it's highly unlikely you'll find "let Marvin Musquin by for second" in last week's playbook.

Dungey's success in Detroit isn't much to write home about, either. But neither was Tomac's in Indianapolis. Dungey has never won the Motor City and lost to Tomac by nearly 12 seconds in 2015 - his best result. And, you know how many laps Dungey has led in the last three rounds? Zero.

Who needs a helmet visor? Not Chad Reed.

Speaking of Musquin, who was formally in second-place, dropped to fourth-place and is now in a third-place tied in points with Cole Seely, he had a heck of a race last week bouncing back from two awful rounds that hit him hard in the Championship hunt. Musquin and Seely sit 49 points behind Dungey and though their title hopes remain iffy the fight for the Championship podium is on. Seely finished fifth continuing a year-long trend of consistency with his eighth Top 5 of the season. He's yet to finish below sixth.

Elsewhere, Chad Reed posted his fourth-straight Top 7 result but a second podium for the year continues to elude him. The veteran is just a point behind Blake Baggett who took fourth last week and six behind Davi Millsaps. A Top 5 year is in reach for all three riders but they'll have to catch Jason Anderson who won Detroit last year and holds a 19 point lead over Millsaps.

A bar-banging good time between Adam Cianciarulo (left) and Zach Osborne (right).

After banging bars with Adam Cianciarulo in practice, Osborne resumed his winning ways in the 250 East passing Joey Savatgy midway through and taking his third victory of the year. He added a little breathing room with Savatgy and now holds a nine point lead. Savatgy has finished second the last two rounds but hasn't won since the opener.

Cianciarulo tweaked his knee after Osborne bumped him off the track last week and initially feared he'd sit out the Main and possibly more. But he powered through for a fifth-place and stays in the Championship hunt. Cianciarulo brings success to Detroit, winning here in 2014 before injury ended his season and title hopes. No news is good news so it appears any lingering knee problems won't prevent him from lining up this week.

Elsewhere Jordan Smith took third last week getting back on the podium since his second-place result in Minneapolis and he's in fourth-place just three points behind Ciaciarulo. Four rounds remain in the 250 East class with just 21 points separating fourth from first place and all four riders have at least two podiums each.

Our Podium Picks for Detroit:

450 class

  1. Eli Tomac
  2. Ryan Dungey
  3. Jason Anderson

250SX East Class

  1. Zach Osborne
  2. Adam Cianciarulo
  3. Joey Savatgy

Check out the track map for Round 12:

Doors to Ford Field open at 12 p.m. (EST) with opening ceremonies at 6:30 p.m. (EST) and the Main Event at 7 p.m. (EST) on Saturday in Detroit. Buy tickets online at the box office. FOX Sports 1 airs Round 12 live.

2017 Supercross Season Standings

450 Class

  1. Ryan Dungey (234)
  2. Eli Tomac (222)
  3. Marvin Musquin (185)
  4. Cole Seely (185)
  5. Jason Anderson (155)
  6. Davi Millsaps (136)
  7. Blake Baggett (131)
  8. Chad Reed (130)
  9. Broc Tickle (116)
  10. Dean Wilson (115)

250SX East Class

  1. Zach Osborne (111)
  2. Joey Savatgy (102)
  3. Adam Cianciarulo (93)
  4. Jordon Smith (90)
  5. Dylan Ferrandis (68)
  6. Alex Martin (60)
  7. Christian Craig (51)
  8. Luke Renzland (50)
  9. Colt Nichols (49)
  10. Anthony Rodriguez (46)