It’s still too early for serious Heisman Trophy talk, and yet, it’s almost irresistible heading into Saturday night’s showdown between Clemson’s Deshaun Watson and Louisville’s Lamar Jackson.

Two top-five teams. Two electrifying quarterbacks. Two tough defenses headed for significant tests.

The winner between No. 3 Louisville and No. 5 Clemson will own the ACC driver’s seat, and almost surely will have one of those Heisman moments voters remember every December.

Last year, LSU’s Leonard Fournette was the Heisman favorite until Week 10, when Alabama held him to 31 yards. Derrick Henry bulldozed for 210 yards that night and eventually took home the bronze trophy.

Stanford tailback Christian McCaffery finished second in the voting and Watson was third. They returned as preseason Heisman favorites this year, along with Fournette — but Jackson is the one who has dominated the highlight reel.

Jackson hurdled a defender for a touchdown at Syracuse and ran right over another in the 63-20 thrashing of Florida State. In four games, he has accounted for 25 touchdowns — 13 passing, 12 rushing — and averages 464 yards of total offense.

“When he touches the ball, you hold your breath because he’s got the ability to change the game on one play,” Clemson coach Dabo Swinney said.

Swinney has called Jackson “a righthanded Michael Vick.”

But after watching Jackson destroy Florida State, Vick tweeted, “Lamar Jackson 5x better than what I was at V-Tech. … Enough said!”

Most of Louisville’s games have been decided by halftime, giving Jackson a breather, yet the Cardinals still lead the nation in scoring offense (63.5 points per game). Clemson counters with the nation’s fifth-best scoring defense (11 points per game).

When these teams met last September in Louisville, Watson was establishing himself as a sophomore Heisman candidate, and Jackson was a freshman in search of more playing time, as Clemson won 20-17.

The 20 points were the fewest the Tigers scored all season. They went 14-1, losing the national title to Alabama in a game that only solidified Watson’s stature as the pre-eminent quarterback in college football.

He became the first college quarterback to pass for 4,000 yards and run for 1,000 in the same season, including a cool 405 and 73 against Alabama.

“He can throw the deep ball, he can be very accurate in the medium and short-range passes, he can run with the ball,” Louisville coach Bobby Petrino said. “So he causes you a lot of issues.”

Besides Watson, Clemson has tailback Wayne Gallman (1,527 rushing yards last season) and high-skilled receivers Mike Williams, Ray-Ray McCloud and Artavis Scott. Even with all that talent, though, the Tigers haven’t been as potent this season.

One factor has been the offensive line’s struggles. And with Watson billed as potential No. 1 overall draft pick, the Tigers have been more cautious running him.

He averaged 22.7 rushing attempts in Clemson’s final three games last year — the ACC title game and the two College Football Playoff contests — compared to 8.8 so far this year.

Meanwhile, Louisville hasn’t hesitated to run Jackson. He had 21 carries vs. Syracuse and 17 vs. Florida State. When quarterbacks run this well, and defenses know they can get burned by that, it opens things up in the passing game. Jackson has taken advantage, much as Watson did last year. Keep in mind, Watson has completed 66.3 percent of his career passes, compared to 56.0 for Jackson.

Clemson has sweated through close wins over Auburn (19-13) and Troy (30-24), but logic says Swinney will take off the reins Saturday, using Watson more like last year. Otherwise, the Tigers could be on the wrong end of one of those Heisman moments, in Death Valley.

Short takes

• Friday brings a Pac-12 North showcase with No. 7 Stanford at No. 10 Washington. Washington QB Jake Browning has completed 70.5 percent of his passes, with 14 TDs and two interceptions, and Stanford is missing its starting cornerbacks, Quenton Meeks and Alijah Holder. But Stanford QB Ryan Burns led a game-saving drive at UCLA last week, and RB Christian McCaffery remains one of the best players in college football.

• Iowa QB C.J. Beathard is too good to get overly concerned about two games. But he completed just 50 percent of his passes against North Dakota State and 52 percent in last week’s 14-7 victory at Rutgers. “When things aren’t going well, sometimes players try to do too much,” coach Kirk Ferentz told the Cedar Rapids Gazette. The Hawkeyes face Northwestern before coming to Minnesota on Oct. 8.

• Michigan coach Jim Harbaugh on Wisconsin’s defense, heading into their top-10 battle Saturday at Michigan Stadium: “They play extremely hard. I had the pleasure of coaching [linebacker] Chris Borland a few years back [with the 49ers], and it’s a team of Chris Borlands. High, high energy. Tough guys that can run. A big, physical team. Very impressed.”

BIG TEN POWER RANKINGS

1. Wisconsin (4-0, 1-0): The Georgia State close call isn’t forgotten, but the victories over LSU and Sparty resonate.

2. Michigan (4-0, 1-0): Wolverines average 52 points per game heading into Saturday’s showdown with Bucky.

3. Ohio State (3-0, 0-0): That’s right, Buckeyes: You snooze (bye week), you lose. Oklahoma was two weeks ago.

4. Nebraska (4-0, 1-0): Cornhuskers fumbled twice at the Northwestern goal line, or it would have been a 25-point rout.

5. Michigan State (2-1, 0-1): Mark Dantonio: “People have said a lot of good things about us lately. Now we’ll take some shots.”

6. Iowa (3-1, 1-0): Close win at Rutgers was disconcerting. So is Matt VandeBerg’s season-ending foot injury.

7. Gophers (3-0, 0-0): Schedule still includes games with six teams below them on this list (all except Indiana).

9. Penn State (2-2, 0-1): Saquon Barkley had 136 total yards vs. Michigan. The rest of the Nittany Lions had 63.

8. Maryland (3-0, 0-0): With Purdue visiting Saturday, the Terps could start 4-0 for first time since 2001.

10. Indiana (2-1, 0-0): Richard Lagow passes for 496 yards, three TDs — with five interceptions — in a loss. That’s so Indiana.

11. Northwestern (1-3, 0-1): Clayton Thorson is a sophomore with room to grow, but his turnovers (five) are piling up.

12. Illinois (1-2, 0-0): Huskers won’t take the Illini lightly because Wes Lunt and Co. upset them last year 14-13.

13. Purdue (2-1, 0-0): Boilermakers had four turnovers, giving them nine in two games, but got needed win over Nevada.

14. Rutgers (2-2, 0-1): Chris Ash’s team is improving, but losing the dynamic Janarion Grant for the year hurts.