It's only the second week of the regular season, but one of Ohio State's biggest games of the year is already here. On Saturday night, the second-ranked Buckeyes will host No. 5 Oklahoma in a primetime showdown at Ohio Stadium.

ESPN College GameDay is in Columbus and kickoff is slated for 7:30 p.m. ET. Until then, here's everything you need to know about the top-five battle between the Buckeyes and Sooners on Saturday night:

Can Dobbins get it done?

It took all of one game for Mike Weber to get Wally Pipp'd.

After missing Ohio State's season-opening victory over Indiana a week ago, the Buckeyes' sophomore running back suddenly finds himself second-string on the team's depth chart. That's largely because Weber's absence vs. the Hoosiers opened the door for true freshman J.K. Dobbins, who rushed for 181 yards in his college football debut.

“Mike Weber practiced again, he’s good to go. To say he’s going to have so many carries, I know I’m going to get asked that a lot, I have no idea,” Meyer said during his call-in radio show on Thursday. “J.K. will start, and we’ll go from there."

Of course, it's one thing to rush for nearly 200 yards vs. Indiana and another to do it against Oklahoma. But the fact that Meyer would move Dobbins ahead of Weber, who rushed for more than 1,000 yards just a season ago, shows how much confidence he has in the freshman back.

"I saw what you saw," Meyer said of Dobbins, a 4-star prospect. "He’s a really good player.”

Mayfield looking for a field day

In Sooners quarterback Baker Mayfield, Ohio State finds itself preparing to face one of the most-talented quarterbacks it will see all season.

A Hesiman Trophy finalist a year ago, Mayfield compiled more than 4,000 yards of total offense and 46 touchdowns in his junior season. And in his 2017 season opener, the senior quarterback completed an impressive 19 of his 20 pass attempts for 329 yards and 3 touchdowns in Oklahoma's 56-7 victory over UTEP.

"We studied him all in the offseason," Meyer said of Mayfield this week. "He's just one of the best players in America."

One factor working in the Buckeyes' favor is that a year ago, Ohio State limited Mayfield to a 17-of-32, 226-yard, 2-touchdown, 2-interception stat line in its rout the Sooners. How Mayfield fares in his second go at the Buckeyes could ultimately determine whether or not Ohio State picks up another victory over Oklahoma.

Goin' Deep

Another week, another debate about J.T. Barrett.

Although the Buckeyes' senior quarterback's stat line (20-for-35, 304 yards, 3 touchdowns and 61 rushing yards and a score) ultimately looked good in Ohio State's victory over the Hoosiers, his first-half performance remained underwhelming.

Bouncing back against the Sooners likely wouldn't prove as easy for Barrett as it was against Indiana. That's why it will be important for the Buckeyes offense to get off to a strong start -- both on the ground and through the air -- in order to keep Barrett from playing from behind.

After his disappointing showing against Clemson in the Fiesta Bowl last season, Saturday night will provide the fifth-year signal-caller with a national stage to once again prove he's capable of keeping Ohio State in national title contention. But if he fails to keep pace, questions will only linger regarding the Buckeyes' upside with Barrett behind center.