COLUMBUS, Ohio (AP) The defending national champions are still an enigma to many, including themselves.
No. 2 Ohio State has won all 10 games this season. Its current winning streak is 23 games.
But the Buckeyes have looked unimpressive at times against unranked teams, while repeating the mantra that playing their best is most important at the end of the season.
That time is approaching as Ohio State (10-0, 6-0 Big Ten, No. 3 CFP) faces its sternest - and first, some would argue - challenge of the season against No. 9 Michigan State (9-1, 5-1, No. 13) Saturday in Ohio Stadium.
''We haven't really been tested,'' Ohio State left tackle Taylor Decker said. ''This is a huge gauge for us going into some of the biggest games at the end of the season, because this is the biggest game we've played yet this season.
''We haven't even played our best yet,'' Decker said. ''We have to focus on that and not what people are talking about.''
The games against Michigan State and Nov. 28 at No.14 Michigan have long been targeted as Ohio State's most important of the season, almost rendering the previous 10 as warmup acts.
If the Buckeyes reach the Big Ten Championship Game, they might face No. 5/6 Iowa.
''It's do or die time, make it or break it these last few games if we want to get what we trained for,'' Ohio State right guard Pat Elflein said. ''It's part of being a Buckeye. You feel the pressure all the time to be the best at everything you do.''
Ohio State has struggled offensively beyond running back Ezekiel Elliott, a Heisman Trophy candidate with 15 straight games of 100-plus yards rushing.
Or maybe the expectations coming off last season can't be met.
''There's probably 10 places like this in America where you keep building a beast and you've got to feed it,'' Ohio State coach Urban Meyer said.
''We know there are issues. This is not a perfect team. I've never seen a perfect team. As a matter of fact, we've got a long way to go,'' he said. ''There are certain areas we're not playing very good, and that's why we practice all the time.''
Besides the inside track to winning the East Division, there are bragging rights at stake. Although Ohio State has won 30 straight regular-season conference games since Meyer became coach in the 2012 season, the Spartans handed him his only Big Ten loss - a 34-24 defeat in the 2013 conference title game that ended Ohio State's 23-game winning streak.
Last season, the 14-ranked Buckeyes went to East Lansing and beat the No. 8 Spartans 49-37. Meyer said it was the best offensive performance of the season.
Decker said he hopes this year's game can have a similar effect.
''If we perform well (Saturday) it will show everybody we're for real because people are questioning how good we really are,'' he said.