The one positive outlier in this underwhelming USC football season has been star junior wide receiver Drake London, and so it was a devastating sight late in the second quarter Saturday when London crumbled to the ground in pain after scoring his second touchdown of the game.

London was carted off the field to the locker room and later carted back to the Trojans sideline in a cast of some sort and using crutches to move around.

"Drake will be out right now until everything is settled, so we'll see where he's at," interim head coach Donte Williams said, referring to waiting on final test results and confirming the injury was to London's right ankle.

Asked if there was fear the injury could be season-ending, especially with only four games remaining on the schedule, Williams acknowledged that potential.

"I mean it's always a fear anytime somebody goes down and you see them go ahead and get the air cast and everything else, so that is a fear," he said.

Arizona cornerback Christian Roland-Wallace came down on the back of London's lower right leg, twisting his ankle awkwardly as the players' momentum carried them to the turf on a 6-yard touchdown reception.

London remained down on the field in obvious pain until the cart was brought out and an air cast was applied to his right leg before he was taken to the locker room.

The entire USC offense -- including QB Kedon Slovis, who was out of the game at that point and ran over from the far sideline -- gathered around the cart in the left corner of the end zone to be with London, as did Roland-Wallace after the Trojans had dissipated.

London buried his face in his jersey as the cart pulled away.

"It's really tough. When they brought the cast I knew it wasn't good ... but once I saw that I knew it was really bad news," Slovis said. "It sucks. The best receiver, the best player on the team, so it hurts a lot, but he has a bright future ahead of him in football. That's the bright side of the situation."

Said Dart, who threw that second TD pass to London: "That sucked. I love Drake just as much on the field as I love him off the field. He's been such a great mentor for me and somebody that I really look up to with just his work ethic and leadership. Seeing a guy go down like that, it really hurt."

London entered the day leading all Power-5 players in receiving yards (1,003), receiving yards per game (143.3), receptions (79) and receptions per game (11.3).

(The only FBS player ahead of him was Western Kentucky's Jerreth Sterns, who had 83 catches for 1,077 yards entering the week).

London had 9 catches for 81 yards and 2 touchdowns in the first half Saturday, bringing his season totals to 88 catches for 1,091 yards and 7 touchdowns in seven and a half games.

"That was horrible. He's on pace to have probably one of the best statistical seasons in college football history if I would guess, and to see him go down was awful and I feel terrible for him," offensive coordinator Graham Harrell said. "It's tough, but for him I feel horrible, for us as a team, the next guy's got to step up and make plays and that's what we expect of them."

USC will look for more production from Gary Bryant Jr. (3 catches for 89 yards and 2 TDs Saturday), Tahj Washington (8 catches for 87 yards) and some players who haven't had as significant a role to this point, like perhaps Kyle Ford, tight end Malcolm Epps and others.

They could also lean more heavily on the run game with Keaontay Ingram (27 carries for 204 yards and a TD Saturday) really emerging as a consistent force on the ground.

"I think we're going to do what we need to do, because at the same time he was out for a series and we still passed the ball, went down and Gary Bryant scored a big-time touchdown on a corner route," Williams said. "We have a lot of guys in here that we have confidence in. Shoot, Tahj Washington was a freshman All-American last year (at Memphis), Gary Bryant's caught big passes, Malcolm Epps caught big passes. We hope that (tight end Michael) Trigg comes back soon, just the list goes on. We have a lot of other guys that need to step up and will step up."

But there is no replacing London.

No receiver on the team even has half his production to this point, with the next closest being Washington (32 catches for 396 yards).

London was a leading candidate for the prestigious Biletnikoff Award and chasing the USC single-season receiving records. ESPN's Todd McShay projected London as a first-round draft pick in his latest mock draft.

"Drake come in every single day and works his butt off. I mean, he treats every single day like game day, so to see a player like that go down, I mean, the whole team felt it," Ingram said. "I could tell some of the guys felt it when I came on the sideline and some of the coaches were holding him back because they just wanted to go see how he was."

Said Dart: "I checked on him at halftime. It's crazy because you could tell it was really hurt, but he wasn't even worried about his self as much as he was about the team, which I think shows a lot about his character. He made sure that all the guys in the locker room at halftime were focused on the task at hand and not worried about him. It shows a lot about his character."