The object is roses, for now

Oscar Lua was there from the start and, along the way, has experienced a series of heart-stopping finishes.

The fifth-year senior linebacker’s arrival at USC coincided with California Coach Jeff Tedford’s first season in Berkeley. Since then, the rivalry between the Trojans and the Golden Bears has intensified and produced classic games nearly every season.

In 2003, for example, Cal kicked a field goal in the third overtime at Berkeley for the victory.

Two years ago at the Coliseum, USC stopped the Golden Bears on their final four plays near the goal line to clinch a pulsating win.

Today’s game between fourth-ranked USC and 17th-ranked Cal has all the makings of another last-play finish.

“You really hope that’s not the case,” Lua said, chuckling. “But when you look at their offense and how it relies on the big play, and you look at our defense and how we try to stop that, it definitely could become one of those games.”

Another nail-biting conclusion would be fitting in a game that will decide the Pacific 10 Conference championship and, at the very least, a berth in the Rose Bowl.

USC is third in the Bowl Championship Series standings and will play the Golden Bears a few hours after No. 1 Ohio State and No. 2 Michigan square off in Columbus, Ohio. A win over Cal would keep the Trojans on track for a possible third consecutive BCS title-game appearance.

“I’m sure in everybody’s mind it is a little bigger because of what’s at stake,” USC quarterback John David Booty said. “The team we’re playing is not really any different to us than another team. It’s just the fact of what’s riding on it.”

USC puts its 31-game home winning streak on the line against a Cal team that is coming off an upset loss at Arizona last week, a defeat that derailed the Golden Bears’ hopes for a shot at the national title.

Cal, however, still has plenty to play for: It has not been to the Rose Bowl since the 1958 season.

But to get to Pasadena on New Year’s Day, Cal must get past a USC team that rebounded from an upset loss at Oregon State with a shutout against Stanford and an impressive win over Oregon.

Cal’s high-flying offense features running back Marshawn Lynch, receiver and kick returner DeSean Jackson and quarterback Nate Longshore.

“They have big plays written all over them,” Lua said. “One slip-up and that could be it with a team this good on offense.”

Lynch averages 109 yards rushing a game and 6.5 yards a carry.

Jackson averages a nation-best 20.7 yards per punt return and has returned four for touchdowns. He has nine touchdown receptions and is averaging a conference-best 18 yards a catch.

The former Long Beach Poly High star told The Times this week that he verbally committed to USC in 2005, but spurned the Trojans for Cal on national signing day because he thought USC coaches had betrayed what he felt was an agreement to keep his decision a secret.

“This is a good opportunity to come into the game and knock USC off,” he said.

Longshore, who played at Canyon Country Canyon High, leads the conference in passing efficiency and has been sacked only 10 times.

USC hopes to counter Cal’s big-play capability with a conference-leading defense that has lately created turnovers and appears to have shored up some of its pass-rushing deficiencies.

“We’re cutting our guys loose more,” said Coach Pete Carroll, who is 18-0 in November games at USC. “We really feel like we’ve zeroed in on our guys ... to use them in some special ways to position them so they can create more.”

USC’s offense might have to rely on a trio of freshman running backs if junior Chauncey Washington is slowed by a knee sprain he suffered against Oregon. C.J. Gable, Stafon Johnson and Allen Bradford all got work in practice this week.

Cal’s defense ranks ninth in the conference and is last in pass defense.

Still, linebacker Desmond Bishop, tackle Brandon Mebane and cornerback Daymeion Hughes, the latter two former Crenshaw High stars, are among the playmakers that have helped the swaggering Golden Bears intercept 20 passes.

“There’s been some good talking in these games -- they have some guys that are really confident,” USC flanker Steve Smith said. “That just brings the best out of us. I’m welcoming the talk.”

Tedford, meanwhile, does not expect a warm welcome at the Coliseum, where Cal has lost twice during his tenure -- by a total of eight points.

In 2002, quarterback Kyle Boller led Cal to an early 18-point lead. But in those pre-replay days, USC scored the first of 27 unanswered points on a “phantom” touchdown pass from Carson Palmer to Kareem Kelly that almost certainly would have been ruled no catch today. The Trojans won, 30-28.

Two years ago, Aaron Rodgers completed 23 consecutive passes and had Cal threatening with a first and goal from the nine-yard line with less than two minutes left. But USC staged a dramatic defensive stand and held on for a 23-17 victory.

“Of course it’s going to be a hostile environment,” Tedford told reporters this week. “Last time we played there, it was a pretty wild scene and I’m sure it’s going to be the same way.”

From start, no doubt, to finish.

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gary.klein@latimes.com