Ohio State shows a vulnerable side

Ohio State still has the swagger of the top-seeded team in the South Regional, but it’s not quite as exaggerated as it was last week.

The nation’s No. 1 ranking at the end of the regular season gave the Buckeyes sky-high confidence entering the NCAA tournament, and they responded by extending their win streak to 19 games. But a close call against Xavier in the second round has cracked their aura of invincibility.

So the Buckeyes (32-3), once considered shoo-ins for the Final Four, are facing questions about whether they can survive upstart Tennessee (24-10), then Memphis (32-3) or Texas A&M; (27-6).

Memphis has a 24-game win streak and Texas A&M; has something of a home-court advantage playing only about 200 miles from its College Station campus.

Ohio State will face No. 5-seeded Tennessee tonight at the Alamodome, and the Buckeyes are keenly aware that another performance like Saturday’s and their visit here will be a short one.

“Every team can beat you here because every team is here for a reason,” Ohio State center Greg Oden said. “You could have a bad game and they could have a great game and hit some crazy shots and you can lose at any point.”

Ohio State defeated Tennessee, 68-66, on Jan. 13 -- but they needed a Ron Lewis three-point basket with 11 seconds left to win at home.

“It’s comforting to know you’ve played them before,” Tennessee guard Dane Bradshaw said. “It does give you confidence because you know you can compete.”

The team with maybe the most confidence entering tonight’s games is No. 3 Texas A&M;, which will face No. 2 Memphis. Some of that stems from a large following of fans who cheered wildly during a practice Wednesday.

The Aggies have a defense that has given up only 127 points in two tournament games and a clutch scorer in guard Acie Law IV.

“I think we’ll probably have more fans here than anyone,” Aggies Coach Billy Gillispie said, “and it may help you get over a couple of tough spots in the game. But it won’t be the ultimate determining factor.”

Memphis has been criticized for building its nation’s-longest win streak against a weak schedule. The Tigers played only six regular-season games against teams that made the tournament -- and went 3-3 in those games.

Gillispie isn’t buying it. He used to coach at Texas El Paso, which plays in Conference USA with Memphis.

“Their league is a lot harder than it gets credit for,” he said. “That may fool some people, it doesn’t fool me.”

Memphis could be without leading scorer Chris Douglas-Roberts, who suffered a sprained ankle in a second-round victory over Nevada. That would certainly put the Tigers at a disadvantage -- but not as much as it might other teams. The Tigers have five other players averaging 8.0 or more points.

But no matter what the recent performance indicates, Ohio State is still the team to beat -- and nobody knows that better than Tennessee, which needs to find an answer for Oden, who had 24 points and 15 rebounds in the Jan. 13 game.

While confident because the Buckeyes have shown signs of vulnerability, the Volunteers are also wary for the same reason.

“They haven’t broken out yet,” Tennessee Coach Bruce Pearl said. “

peter.yoon@latimes.com