Posted by ESPN.com's Adam Rittenberg

COLUMBUS, Ohio -- Instant analysis from USC's 18-15 victory against Ohio State at Ohio Stadium.

How the game was won: Backed up to his own 4-yard line, USC freshman quarterback Matt Barkley led a masterful drive against an Ohio State defense that had dominated most of the game. With help from junior tailback Joe McKnight, who made several huge plays, USC went 86 yards in 14 plays and drained 6:10 off the clock. The Trojans finally overcame their terrible field position, while Terrelle Pryor and the Buckeyes never could take advantage of theirs.

Turning point: Facing second-and-19 from the USC 4-yard line, McKnight surged for an 11-yard gain and then caught a 21-yard pass from Barkley for the first down. A second turning point came on fourth-and-inches from the Ohio State 28-yard line, when Barkley sneaked for the first down, his third conversion of the game.

Player of the game: Barkley deserves a ton of credit, but this has to go to McKnight, who came back from cramps in the third quarter to make several key plays on USC's decisive drive. The junior had 61 rushing yards and 45 receiving yards in the victory, but the numbers don't show how much he meant to USC.

Second guessing: Ohio State didn't use Terrelle Pryor as a runner nearly enough. Pryor is always at his best on the move, but he once again tried to be a pocket passer and failed. The Buckeyes couldn't capitalize on favorable field position throughout the second half and scored only one touchdown.

What it means: USC remains the best big-game team in the country, and it has something very special in Barkley, who led his team to victory in an extremely tough environment. The Trojans remain on track for a possible national championship push despite losing the core from last year's team. This is a huge blow for Ohio State, which controlled the tempo and played its type of game (defense, field position, special teams). Pryor will take much of the heat for this one after failing to consistently move the offense. Another big-game loss for the Big Ten, though USC was extremely fortunate to escape Columbus with a win.