Just eight of the 353 Division I men's basketball teams still have a perfect record through Week 5.
While conference play has started (and temporarily been put on hold) in the ACC and Big Ten, something will have to give once it resumes (or starts, depending on the conference). Someone has to lose when No. 3 Ohio State (9-0) and No. 4 Maryland (10-0) play each other.
Plus, only two teams in the country went undefeated in conference play last season — if you answered Wofford and Gonzaga, you answered correctly — so losses are almost guaranteed for even the best teams in a given conference.
We went through every undefeated team's remaining December schedule and picked out its most difficult game this month. If these eight unbeaten teams want to carry their undefeated record into the New Year, they'll have to get past these tough opponents that lie ahead.
No. 1 Louisville (9-0)
Toughest remaining game in December: Saturday, Dec. 28, at No. 8 Kentucky
The in-state rivalry between Louisville and Kentucky, which is played annually at one of the schools' home arenas on an alternating basis, is one of the best men's basketball games every December. Kentucky has won the last two meetings — a 29-point win in Lexington in 2017 and a 13-point win in Louisville last winter — and this will be the first time Louisville has been the higher-ranked team in the matchup since the 2013-14 season, when No. 18 Kentucky beat No. 6 Louisville in the regular season before the No. 8 seed 'Cats upset the No. 4 seed Cardinals in the Sweet 16.
Evansville has already proven that Kentucky can be beaten inside Rupp Arena. So the No. 1-ranked team in the country isn't setting its sights on something unprecedented, but it won't be an easy feat either.
The game projects to be a toss-up. Louisville is projected to win 67-66 with a 51 percent chance of victory, according to kenpom.com. These are two of the 10 strongest defensive teams in the country, so expect a potentially low-possession game with few easy looks, especially inside the arc.
If you're looking for a potential separator between the in-state rivals, we'd highlight 3-point shooting. Louisville is both willing (37.9 percent of its shots are threes) and able (39.1 3-point percentage) from distance, while the same can't be said for Kentucky (27.4 percent of its shots are from three, where it shoots 29 percent).
No. 3 Ohio State (9-0)
Toughest remaining game in December: Saturday, Dec. 21, vs. No. 8 Kentucky (Las Vegas, NV)
Kentucky has the opportunity to play spoiler on consecutive Saturdays in December, facing Ohio State in the CBS Sports Classic in Las Vegas a week before hosting Louisville. The Wildcats might represent the Buckeyes' strongest opponent to date this season, but Ohio State might be the most proven team in the country with wins over No. 17 North Carolina, No. 20 Villanova, Penn State and Cincinnati — all of whom rank in the top 50 on kenpom.com as of Monday morning.
Ohio State has beaten its two best opponents — UNC and 'Nova — by 25 points (including a road win in Chapel Hill) so it's hard to find many inefficiencies in the country's No. 3-ranked team. The Buckeyes have already faced Kentucky-level size in North Carolina, and they already ran the second-most efficient offensive team in the country (Villanova) out of the gym. Ohio State also held an All-Big Ten performer, Penn State's Lamar Stevens, to 11 points on just eight shot attempts in their first Big Ten win of the season.
No. 4 Maryland (10-0)
Toughest remaining game in December: Thursday, Dec. 19, at No. 22 Seton Hall
Seton Hall's profile nationally has diminished slightly after three non-conference losses. But two of them were against preseason top-15 teams by one possession. The third was in a rare instance where the Pirates played the same team (Iowa State) in consecutive non-conference games, winning the first and losing the second.
Excluding the game in which Seton Hall's potential All-American senior guard Myles Powell got injured against Stony Brook, he has scored 27, 37, 26, 23, 32, 18, 24 and 19 points in the Pirates' other eight games — which gave him the sixth-highest points per game average in the nation.
That kind of one-man firepower, plus the 3-point efficiency of teammates Myles Cale (40 percent on 25 attempts), Sandro Mamukelashvili (43.5 percent on 23 attempts), Tyrese Samuel (43.8 percent on 16 attempts) and Shavar Reynolds (57.1 percent on 14 attempts) is enough to keep Seton Hall competitive in essentially every game it will play this season.
Mamukelashvili's 3-point shooting will draw Maryland's Jalen Smith and Makhi Mitchell — two elite shot-blockers — away from the rim and potentially open driving lanes for his teammates.
No. 12 Auburn (8-0)
Toughest remaining game in December: Thursday, Dec.19, vs. N.C. State
The farthest that Auburn has to travel for a game in December is Birmingham, which is just over two hours away. So as long as the Tigers can take care of business at home, and in their semi-home game against Saint Louis, they can bring an undefeated record with them into 2020. A home date with N.C. State will likely be the toughest of their remaining games this month.
The Wolfpack won 78-71 in Raleigh last season and boast the ninth-most efficient offense in the country, as of Tuesday morning. Senior C.J. Bryce is scoring in bunches (15.8 points per game) and doing so efficiently (114.6 offensive rating), while junior Braxton Beverly's 3-point percentage has climbed nearly 10 percent from last season (34.7 percent on 219 attempts last season to 43.9 percent on 41 attempts through nine games).
Even though N.C. State narrowly missed the NCAA tournament last season while Auburn went to the Final Four, these two rosters are similarly veteran-laden. Auburn ranks 59th in kenpom.com's experience statistic, one spot ahead of N.C. State. So don't expect to hear the phrase "freshman mistake" too often on the broadcast.
No. 18 Butler (9-0)
Toughest remaining game in December: Tuesday, Dec.10, at No. 11 Baylor
It's pretty impressive that Butler and Ohio State are on this list together as former Butler coach Chris Holtmann has his Buckeyes on pace to potentially eclipse 25 wins for the first time since the 2013 season. His successor, LaVall Jordan, has engineered a Bulldogs offense that's ranked 12th in adjusted offensive efficiency, which would be the program's best ranking since 2007.
Butler already owns wins over Minnesota, Missouri, Stanford, Ole Miss and Florida. A road win at Baylor would be the most impressive of that group if the Bulldogs can keep the Bears off the offensive glass (37.6 offensive rebounding percentage, the seventh-best in the country) and take care of the ball (Baylor forces turnovers on 24.2 percent of opponent's possessions).
Butler's senior guard Kamar Baldwin is playing the best basketball of his career, scoring a team-high 16.9 points per game while nearly being a member of the 50/40/90 club — 48.7 percent from the field, 41.7 percent from three and 95.5 percent from the free-throw line.
No. 25 San Diego State (10-0)
Toughest remaining game in December: Saturday, Dec. 21 vs. Utah (Los Angeles, CA)
If you're a fan of predictive metrics, then you'll appreciate that kenpom.com projects San Diego State to be an underdog in just one game the rest of the season — Jan. 4 at reigning Mountain West champion Utah State. Now, does that mean the Aztecs will go 28-1 in the regular season? Almost certainly not, losses happen.
But that tells you the potential for San Diego State.
After a home game against non-DI San Diego Christian on Wednesday, the Aztecs will play Utah in L.A. on Saturday. Given the Utes' No. 193-ranked defense, San Diego State could potentially win this game going away if its top-25 defense plays up to its potential. It ranks in the top 20 nationally in defensive rebounding percentage (77.2 percent), defensive 3-point percentage (26.9 percent) and opponent effective field goal percentage (42.6 percent) so easy looks and second-chance opportunities will be hard to come by against the Aztecs.
Toughest remaining game in December: Sunday, Dec. 29, at LSU
The Flames finish 2019 with arguably their three toughest non-conference games in succession: at Vanderbilt, against Towson on a neutral court and at LSU. The trip to Baton Rouge will be a difficult task as Liberty will be asked to try to slow down LSU's tenth-ranked offense on its home court. The Tigers are a few bounces away from being undefeated themselves, with their only losses coming by two points at VCU and against Utah State on a neutral court.
LSU is shooting a ridiculous 61.9 percent on shots inside the arc this season, thanks to the efficient short-range shooting of Darius Days (85 percent), Emmitt Williams (70.8 percent) and Skylar Mays (64.9 percent). That makes December 29 arguably the most important game of the regular season for Liberty big man Scottie James, 6-8, who's the Flames' tallest rotation player and averages a team-best 10.5 points and 7.6 rebounds per game.
Liberty beat Mississippi State in the first round of last season's NCAA tournament, and the Flames' No. 71 ranking on kenpom.com suggests they could be competitive if they played in a bigger conference (for reference, Ole Miss is ranked one spot ahead of Liberty at No. 70 and kenpom.com projects Ole Miss to finish 8-10 in the SEC this season).
Toughest remaining game in December: Saturday, Dec. 14, vs. Radford (Akron, OH)
Duquesne is coming off of a 36-point win over Columbia on Monday night in which four of its five starters had an offensive rating of at least 148. (For perspective, a season-long offensive rating of 120 is really good.)
The Dukes are blocking 19.2 percent of opponents' shots — the highest percentage in the country — and opponents are making just 24.8 percent of their threes. On offense, Duquesne has thrived by making a high percentage of their twos – 57.4 percent, to be exact.
Radford (No. 129 on kenpom.com) will be the second-highest rated team Duquesne has played this season, and while the Highlanders started just 3-5 this season, one of those three wins was by 11 points at Northwestern. They've also played competitively against top-100 competition Liberty and UNC Greensboro.