Floyd, USC are not sure what to expect

Tim Floyd’s USC teams have had one recurring problem in season openers.

Namely, the finish.

Two years ago, the Trojans forced overtime against Cal State Northridge with a frantic second-half rally, only to go cold in the extra period.

Last year, USC couldn’t contain speedy South Carolina guard Tre’ Kelley’s repeated forays into the lane and suffered another overtime disappointment.

Even the arrival of celebrated freshman O.J. Mayo hasn’t convinced Floyd that his team is bound for a more agreeable outcome today when No. 18 USC opens its season against Mercer at the Galen Center.

“I’d take an overtime right now and take our chances,” Floyd quipped this week.

While Mayo has proven to be a singular talent in practices and scrimmages, the Trojans still find themselves confronted with multiple worries. They are a freshman- and sophomore-laden team whose development has been slowed by a slew of injuries.

Sophomore guard Daniel Hackett (broken jaw) and freshman center Mamadou Diarra (hernia) will not play today. Three other players -- sophomore forward Taj Gibson, freshman guard Marcus Simmons and freshman forward Davon Jefferson -- will play at less than full strength after battling various ailments the last few weeks.

The wave of injuries has forced Floyd to simplify his offensive and defensive schemes, a tactical switch that he said could leave the young Trojans playing something resembling “street ball” early in the season.

The simplification also could have unexpected benefits, however. Floyd spent much of preseason practice his first two seasons at USC meticulously installing his defense at the expense of other parts of the game.

“I just think the amount of emphasis early on on what we feel will be important over the long haul in trying to get established on the defensive end and not being able to spend as much time in other areas kept us from advancing our team,” he acknowledged in August.

Another reason the Trojans have struggled at the outset of recent seasons is because they’ve continually been a team in transition. Floyd’s first team had four returning scholarship players with a combined five years of Division I experience. His second team lacked a pure point guard in the wake of the shooting death of Ryan Francis and the academic ineligibility of Gabe Pruitt.

These Trojans feature seven freshmen, five sophomores, three juniors -- and no seniors.

“Each year we’ve had so many freshmen come in,” junior forward Keith Wilkinson said. “We haven’t had a lot of guys coming back, so it’s always teaching and re-teaching and getting new guys involved in it, so it takes a while. It’s a process.”

The process has benefited from the arrival of Mayo, whose debut may finally silence the skeptics who long held that he would spend this year playing overseas or embarking on a barnstorming tour before entering the NBA draft. But Mayo had concerns of his own entering today: first-game jitters.

“I’m usually nervous before every game, so I’ll probably be nervous,” Mayo said. “I’ll just try to think of winning and hopefully it will take away the butterflies.”

A victory could help assuage the fears of Floyd, who acknowledged that he doesn’t know quite what to expect from his team.

“We’ve got a lot of ifs,” Floyd said. “We’ve got more ifs than anybody. That’s what makes it fun.”

Then came a long pause.

“I guess,” he finally continued, shaking his head.

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TODAY

vs. Mercer, 1 p.m.

Site -- Galen Center.

Radio -- 710.

Records (2006-07) -- USC 25-12; Mercer 13-17.

Update -- As expected, Hackett had the wire removed from his broken jaw Friday and will begin practicing with the Trojans next week. Junior forward RouSean Cromwell returned to practice from his leg injury and is expected to be available today.

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ben.bolch@latimes.com