That finally changed in the fourth quarter of the highly regarded freshman's sixth game for Southern California.
McKnight, who prompted comparisons to Reggie Bush with his shifty moves and speed at John Curtis High in River Ridge, La., set up the game's final 10 points with a 45-yard punt return and 59-yard run Saturday, igniting No. 10 Southern Cal to a 20-13 victory over Arizona.
"To get a good win and finish it strong at the end was really cool," Southern Cal coach Pete Carroll said. "We're very fortunate."
Mark Sanchez, a third-year sophomore making his first start, threw a 25-yard scoring pass to Fred Davis with 10:47 remaining on the first play after McKnight electrified the Los Angeles Coliseum crowd of 84,671 with his punt return.
Suddenly, the Trojans led 17-13. Their defense would hold the Wildcats without a first down after that.
"The seniors were on the sideline, everybody's on the sideline saying we just need a play just to get everybody up," McKnight said. "I really haven't been proving to people what I can do, so I hope I prove it to them now and I prove to the seniors that I can play with them."
McKnight's 59-yard run set up David Buehler's 23-yard field goal with 57 seconds left that completed the scoring.
"Joe McKnight, you saw him finally, you saw what we've been talking about," Carroll said. "He's a fantastic football player. It just hasn't happened for him yet. It's just a confidence deal, it's just getting out there."
The game was Southern Cal's first since a shocking 24-23 loss to 41-point underdog Stanford, snapping the Trojans' 35-game winning streak at home. It appeared they were going to go down again, this time as 21-point favorites, before McKnight's first big play.
Southern Cal (5-1, 3-1 Pac-10) won despite being held to 12 total yards in the second quarter and 50 in the third period.
The Wildcats (2-5, 1-3) were clearly the better team until McKnight's punt return, having overcome a 10-0 deficit to take a 13-10 lead.