1. Michigan State (13-1)

Season so far: The Spartans are No. 1 in the nation after cruising past the likes of Kansas, Providence Louisville and Florida but dropped their Big Ten opener, badly, at unranked Iowa on Tuesday, one day after coach Tom Izzo’s father died.

– the ultra-versatile Denzel Valentine, who had a minor knee surgery earlier this month.

2. Purdue (13-1)

Season so far: The Boilermakers have the nation’s most efficient defense, per analyst Ken Pomeroy, and arguably its best frontcourt.

What’s ahead: Purdue has played the second-toughest nonconference schedule among Big Ten teams. Will the result be fatigue or battle-tested toughness?

3. Iowa (10-3)

Season so far: The Hawkeyes have won every game at home, don’t have any embarrassing losses and are about to hit the national rankings after routing the No. 1 Spartans 83-70 on Tuesday.

What’s ahead: The senior-laden squad could shoot its way into contention or struggle from a lack of depth over the course of a long, grueling season.

4. Maryland (11-1)

Season so far: Sophomore guard Melo Trimble, the Big Ten preseason Player of the Year, and 6-11 center Diamond Stone, one of the league’s most anticipated freshmen, have been the difference-makers.

What’s ahead: The Terrapins will have to seize games like the one they lost at North Carolina in early December if they want to be considered national title contenders.

5. Michigan (10-3)

Season so far: The Wolverines are healthy and finding a rhythm after dropping a program-high 17 three-pointers in a 96-60 victory over Bryant last week.

What’s ahead: Senior guard Caris LeVert has shown he’s primed to have the kind of season he delivered before a foot injury ended his campaign a year ago, but the Wolverines must get out of their own way defensively.

6. Ohio State (8-5)

Season so far: Youth contributed heavily to an ugly four-game losing streak, which included losses to Texas-Arlington and Louisiana Tech … and then lifted the Buckeyes to a seven-point, neutral-court victory over No. 4 Kentucky.

What’s ahead: Suddenly the Buckeyes are looking pretty good, and there are plenty of opportunities to gain steam with Minnesota, Illinois, Northwestern and Rutgers accounting for four of the Buckeyes’ first five league games.

7. Northwestern (12-1)

Season so far: Don’t look now, but Northwestern has only one loss — to No. 7 North Carolina — despite losing wing Vic Law for the season because of a torn labrum.

What’s ahead: If the Wildcats can continue their climb, they’ll make their first NCAA tournament ever in March.

8. Indiana (10-3)

Season so far: The Hoosiers finally snagged a résumé-worthy victory over Notre Dame, but the much-needed win doesn’t erase the weirdness of the rest of their nonconference slate.

What’s ahead: One of the major story lines of the preseason was that Indiana’s defense had improved. Offensively, the Hoosiers are more dynamic, but there is much to prove on the other end.

9. Illinois (8-5)

Season so far: Once again, the Illini have been ravaged by injuries and it’s led to five losses. Six players have been sidelined at some point this year.

What’s ahead: Kendrick Nunn is back and in a groove, and Malcolm Hill has averaged 24 points in the past four games. That productive duo of junior guards could lift Illinois out of its early-season rut.

10. Wisconsin (8-6)

Season so far: This is not the same team that charged to the national championship game a year ago — these Badgers are less experienced and less disciplined, have fallen to the likes of Milwaukee and Western Illinois and wasted an opportunity at home vs. Purdue on Tuesday.

What’s ahead: Wisconsin hasn’t dropped farther than fourth in the league in 15 years, but now the Badgers will have to try to figure it out without legendary coach Bo Ryan, who retired in December. Longtime assistant Greg Gard, now the interim coach, has his work cut out for him.

11. Nebraska (8-5)

Season so far: A roster filled with 10 freshmen and sophomores have prevented the Cornhuskers from stringing together a winning streak since a three-game run in November.

What’s ahead: Victories over Tennessee and Rhode Island showed promise, but coach Tim Miles will have to figure out how to replace the nearly 30 percent of offensive production the Huskers lost from grad Terran Petteway.

12. Penn State (9-4)

Season so far: The Nittany Lions haven’t won a single game of note, but they’re not getting killed either. A loss to Colorado on a neutral court last week came by a single point.

What’s ahead: Pat Chambers’ bunch has salivated at the idea of taking the next step since he took the job four years ago. But so far the Nittany Lions haven’t made the jump.

13. Minnesota (6-6)

Season so far: Youth and major roster turnover led to four losses in the past five games, including three guarantee games at home.

What’s ahead: Their talented freshmen corps could find enough chemistry to steal a few games in league play.

14. Rutgers (6-7)

Season so far: The Scarlet Knights’ offense has even less firepower than it did a season ago.

What’s ahead: Intriguing freshman guard Corey Sanders will make a bad season slightly easier to stomach, but not much.