For the first time in 15 years, USC and UCLA are meeting for their crosstown rivalry showdown while both nationally ranked.

In fact, a few weeks ago the No. 21 Trojans and No. 12 Bruins were both ranked inside the top 5 of the AP poll.

Add in the fact that USC has already announced a sellout for the Galen Center on Saturday night, and yes, there's no denying this game carries some extra weight.

"Very much so," Trojans center Chevez Goodwin said. "It's UCLA vs. USC so there's always excitement. It's a battle for L.A., crosstown showdown, every name you can think of for it. This is going to be exciting. I can't wait to play in it with an actual crowd this time. Last year we played it was just a library in the gym, so there will be actual fans -- I can't wait to play."

The Trojans (20-4, 9-4 Pac-12) also can't wait for another opportunity at the statement win that is still lacking from their overall impressive season resume. A brutal shooting night cost them a chance to take down a top-5 Arizona team on the road last weekend, so the Bruins (17-4, 9-3) represent an important opportunity as it relates to NCAA tournament seeding and general momentum.

"This makes it a little different than other games because we're both so highly ranked and this is a game for our team we really need because we haven't beat a ranked opponent yet," guard Ethan Anderson said. "This will be our second ranked opponent and I think this will really prove to the world and to ourselves that we are who we say we are and we deserved that top 5 ranking that we had earlier in the season."

The big storyline is whether -- or how much -- junior forward Isaiah Mobley will be able to play after sustaining a broken nose in that loss at Arizona and sitting out the Trojans' tenser-than-expected 74-68 win over Pacific on Tuesday.

Mobley went through the non-contact portions of practice Friday and stayed after to get extra shots up and get used to wearing the fitted protective face mask he'll wear if he's able to take the court Saturday night. He was not made available for interviews and coach Andy Enfield continued to call him a "game-time decision."

"Hopefully he can play. It will be day to day, game-time decision. He has a mask, it's fitted to his face. He had a tough nose break against Arizona. It was a very physical game we played on the road, and [this] will be physical as well, so we need to protect him and if he's able to go he will," Enfield said.

It would be a surprise if Mobley isn't out there given the stakes of this game and his undeniable importance to this team. He leads USC in scoring (14.7 points per game), rebounding (8.5 per game) and is a close second in assists (3.2 per game).

The Trojans clearly struggled to adjust to his absence Tuesday, trailing by 13 points early in the second half before pulling out the win against a Pacific team that sits near the bottom of the West Coast Conference standings.

"Obviously, he's our best player. He leads us in every category so it was a little different not having him out there, but it's a team sport, not an individual sport, so I feel we'll be fine with or without him," Goodwin said. "We'd love to have him out there obviously, but if he's not out there we just have to do what we do best and go out there and play our game."

Said Anderson: "He leads us in everything so it was a really big thing, we've never played without him before. So that last game was [a] new feel not playing with your top scorer, rebounder and assister, so definitely a new adjustment, but we've [had] some practice days in without him now that we know the lineups we're going to use [if he's not available] and how to play together so we'll be ready."

Again, it would be a surprise if Mobley is not active Saturday night, but even if he does play there remains the question of how large a role he could shoulder and how comfortable he is with the facemask and the injury.

"The first part, he hasn't practiced all week, and second, he hasn't worn a mask in a game before or practiced hard with it. So it will be an adjustment, but Isaiah's a big-time basketball player and he'll be ready for the moment," Enfield said. "He got up and down the court just a little bit [Friday], non-contact and did some shooting, but want to prepare him for [Saturday]. If he can play we want him to be fresh and ready to go."

This is a Bruins roster that USC is very familiar with, as they returned their top seven scorers from the squad that made it all the way to the Final Four last year. Guards Johnny Juzang (18.1 points per game), Jaime Jaquez (13.2), Jules Bernard (12.8) and Tyger Campbell (11.2) lead the way for a team that was rolling until back-to-back losses at Arizona and Arizona State (triple overtime) last week that dropped the Bruins nine spots in the national rankings.

USC has won the last four meetings against UCLA -- including a couple memorable buzzer-beaters the last two seasons -- but the players say the past is the past.

"It definitely means something just in terms of we know that we can beat them and we know that we've done it before, but it also doesn't mean anything because this game's a whole new game," Anderson said. "None of those games in the past are going to carry over here. We have to come out and earn it all over again."

This is the first of two meeting between the rivals this season, with the rematch at Pauley Pavilion set to close out the regular-season schedule.

While the teams are plenty familiar with each other, this will nonetheless be a new experience for several Trojans, even those that were part of the matchups last season, as those games were played without fans. The atmosphere will be totally different Saturday night in Galen Center.

"It felt like another game to me [last year] -- it didn't feel like a rivalry. The only thing that changed was Coach Enfield was yelling more than usual. Other than that, though, it was a regular game to me. This year hopefully I can learn a little more about it, just experience it more for myself in all its capacity," Goodwin said.

Said Anderson: "We've been emphasizing the details and how hard we have to play to win this game. That's really a focus. The main thing I've expressed to our guys [now] that I've played in this game a couple times is that every play counts. Play at your hardest, but also at the same time there's no reason to come out here and be nervous -- it's just Saturday night basketball like we've been doing for months."