SAN DIEGO — In the beginning, Lute Olson had the firmer handshake, and Steve Fisher was OK with that.

Fisher’s San Diego State Aztecs, the ones that went just 5-23 in his first season of 1999-2000, signed a two-year deal to play Arizona. They needed big teams on the schedule, Fisher said then, and results didn’t matter then as much as the exposure.

The fact that Arizona and SDSU might someday play in the Sweet 16, as they will tonight as possibly the top two programs in the West, wasn’t on anybody’s minds at the time.

“You know, when we came out here, and Lute said he’d play us, I don’t know if it was anything other than, ‘I have a home in Coronado, so we’ll go over, it’ll be a nice trip, and we know we’re going to win,’ ” Fisher said. “That sort of thing. And they did.”

UA swept the initial series, bringing Luke Walton home for an eight-point win in 2002-03 and winning the return game at McKale Center by 12. Then the Wildcats agreed to a four-year deal starting in 2006-07, and that started out pretty well for them, too.

Arizona won with Olson’s final team in 2006-07, with interim coach Kevin O’Neill in 2007-08 and with second interim head coach Russ Pennell the following season. But then San Diego State broke through for its first win over Arizona in 26 years — although that was against Sean Miller’s first team in 2009-10.

When the Aztecs won again in 2011-12, that was after Derrick Williams’ departure had exposed what was a still-rebuilding program, and one that was also saddled with recruiting disappointments in freshmen Josiah Turner and Sidiki Johnson.

But all that’s over now. The Wildcats are back in full form, carrying the No. 1 ranking for eight weeks in midseason and earning the No. 1 seed in the West Region.

And San Diego State is in better shape than ever, having put together a 20-game winning streak after losing to UA back in November, its long, athletic lineup creating havoc defensively in much the same way that the Wildcats do to their opponents.

The Aztecs have become one of just 10 schools nationally to have won at least 23 games and advanced to the NCAA tournament in each of the last four seasons — and they are 11-4 in that time against the other nine teams who have done so.

So Arizona is rolling. San Diego State is rolling.

That makes tonight’s game a showdown, not only for an Elite Eight berth but also, arguably, for the chance to boast dominance in the West.

“I definitely think this game has a lot to do with bragging rights,” said UA guard Gabe York, a Southern California native. “They’re a great basketball team, and if you think about the West Coast teams, they’re one of the top two teams on the West Coast. It’s definitely going to be a battle.”

The evidence that Arizona and SDSU are the West’s two top programs, at least at the moment, is pretty strong.

San Diego State has a 41-game winning streak over teams from California, including wins over UCLA and USC last season. They have won the Mountain West Conference three times in the past four seasons, too.

Arizona, meanwhile, has won the Pac-10 or Pac-12 regular-season title twice in that same period and beat UCLA at Pauley Pavilion this season (though the Bruins won the 2013 Pac-12 regular-season title and beat Arizona in the last two Pac-12 tournaments).

In the West, who’s left?

Gonzaga? The Zags whipped Arizona two years ago in Seattle but were destroyed by the Wildcats on Sunday in the round of 32.

Oregon? The Ducks were expected to challenge UA for the Pac-12 title, and the beat Arizona in their home regular-season finale March 8, but they underachieved much of the season and didn’t make the Sweet 16.

Cal? The Bears handed UA its first loss of the season, but that was the one when Brandon Ashley was lost for the season and Nick Johnson went 1 for 14 from the field. Oh, and the Bears didn’t make the NCAA tournament.

Stanford? The Cardinal reached the Sweet 16 this season but … has lost to the Wildcats nine straight times.

UNLV? The Rebels dropped off dramatically this season, and lost to both San Diego State twice and to UA once.

So it is, then, that San Diego State is right there with Arizona and possibly, depending on your point of view, with UCLA.

“San Diego State is a great team. We’re a great team,” said UA guard Jordin Mayes, a Los Angeles product. “There’s always battles between the two teams.”

There’s one more piece of evidence that Arizona and SDSU are currently on top, and it has nothing to do with the players or coaches.

While UCLA has played in front of thousands of empty seats at Pauley Pavilion this season, the Wildcats sold out all but three of their 18 home games at McKale — and the Aztecs have sold out Viejas Arena for all games in the past two seasons, and regularly over the past four.

Even on a quiet day inside Viejas Arena, Fisher can see evidence of that passion outside, when folks line up on Montezuma Mesa.

“I can look out my (office) window and see the ticket window,” Fisher said. “During the season sometimes I would ask, ‘What concert is there? They would say, ‘No, that’s for us. That’s for our game.’

“That doesn’t surprise me.”

Sportswriter for the Arizona Daily Star covering Arizona Wildcats basketball