MUSIC : Australian Conductor to Lead Symphony Tonight : Tryout: Stuart Challender is viewed as a dark horse candidate to succeed Keith Clark as permanent director of Pacific Symphony.

In every good race, there is a dark horse--in the ongoing contest to replace Keith Clark as music director of the Pacific Symphony, that distinction may belong to Stuart Challender, chief conductor of the Sydney (Australia) Symphony.

In fact, Challender, who will lead the Pacific today and Thursday at the Orange County Performing Arts Center, was never supposed to be in the race at all.

He’s there now because Zdenek Macal of Laguna Niguel, originally announced as this week’s guest conductor, decided that he didn’t want the director’s job after all. He agreed to release the dates, according to an orchestra spokesperson, so that Challender could be considered.

“The Pacific Symphony rang me up two or three months ago,” Challender said in a recent interview (stressing that they called him , not the other way around). “They said Mr. Macal had canceled and was I interested in coming? They knew me from last year’s Sydney Symphony tour,” which began in Orange County.

Was he aware that the orchestra was conducting a search for a new music director?

“I did know that, he said. “But they rang me.”

Is he interested in the job?

“Yes, but we’re not talking about that at the moment,” he said. “I haven’t thought about it really. I certainly enjoy working in the States. It depends on how we could arrange it in terms of time commitment with Sydney . . . I really don’t just know . . . If everything goes well at the concerts, we might sit down and talk. . . . “

Challender was on the phone from Tokyo where he was relaxing after having stepped in for an ill Seiji Ozawa for three concerts in Hong Kong with the Boston Symphony. (On one of the programs, he split podium duties with Carl St. Clair, the orchestra’s assistant conductor, who is scheduled to try out with the Pacific Symphony on Jan. 31 and Feb. 1.)

A student of Zen Buddhism, Challender had a very good time in Kyoto, visiting Zen temples. “But it was a little bit hurried,” he said. “I went by bus--which is not a good idea. The traffic is unbelievable.”

His career, he said, has been going well. In the past year, he has conducted about 30 concerts in Australia and has guested in Europe. After Costa Mesa, he heads to Chicago to conduct the Chicago Symphony.

“This is all very good for me--and indeed good for the Sydney Symphony--to be seen to be working overseas a lot,” he said. “I think it’s very important that we tour. For so many years, we felt very much out on a limb, by ourselves. It’s very good for musicians and artists to get out there and show our wares and compete in the big world.

“It’s only 12 hours on that wonderful direct L.A.-to-Sydney flight. We’re beginning to feel much more part of the real world.”

When he returns home from Chicago, he faces major challenges: first, Wagner’s “Tristan und Isolde” for the Australian Opera, and then he will lead the complete three-act version of Berg’s “Lulu” in its first Australian presentation.

The opera will be part of a two-month festival, “Mahler, Vienna and the 20th Century.” Challender believes his country is ready for such major challenges, because the music scene there steadily has been upgraded.

“The major trend in Australia is that the standards are rising, and rising rapidly. This thrills me,” he said. “For many years we kept saying, ‘This isn’t good enough.’ We seemed to get no support from the older generation who were happy to go on with things the way they were. That’s all changing.

“There is a new generation of managers and orchestra personnel and conductors and musicians who all want to see things get a lot, lot better. We’re working very hard. But like all change, it’s difficult. There is an older guard who thinks, ‘Why change? Things have been very fine.’ ”

Upgrading, of course, costs money.

“One of the first things the new regime did was to raise orchestra salaries,” Challender said. “They had been allowed to fall behind the rest of the work force quite badly. We realized that if wanted to raise the standards, we had to pay for it. So we found more money, which was a miracle--I’m still not sure where it came from--and gave our musicians a very substantial increase in salary.”

He added: “We get more government subsidy than American orchestras, but we still have to work very hard to get increased funding. We can’t actually use private money to pay for salaries. That can only be used to fund special programs because the orchestra players are attached to the government through the government-funded radio station and so are classified as public servants. There are problems there to be solved.”

Challender has put an Australian work on the Pacific program--Richard Mills’ “Bamaga Dyptich”--to replace American composer John Corigliano’s “Variations on an Ostinato.”

“I simply did not have enough time to learn that new piece, which I had never done before,” Challender said. “The (Pacific) agreed to replace it with an Australian work by Richard Mills, a young Australian, a very fine, young composer, one of our best.”

Challender described the 15-minute “Dyptich” as “a brilliant orchestra showpiece” for large orchestra.

“It’s meant to be a pictorial and psychological description of the breaking of the dry season in northern Australia,” he said. “If you’ve ever experienced those few weeks of intense heat and dryness that lead up to the monsoon season in the tropical parts of the world, you know what it means to convey the feelings that are associated with that heady atmosphere.

“It’s hard to describe it in words. It’s very easy to describe the pictorial part, which is so realistic: rain on the roof and thunder and wind in the palm trees. But the psychological part is very deep and personal to the composer who lives in a tropical part of Australia and who has experienced it many times: What it does on the people, the release and tremendous emotional outpouring when finally the rain does start to come down. Everyone goes out and gets sopping wet.”

He said that while he “never analyzed” how he works in rehearsals, he said that “it’s very important to have a very clear idea of what you want before you enter the rehearsal room, even though perhaps you may change slightly this ideal. The acoustical properties of the hall play a big role in the work you do.

“But I like to let the musicians’ personalities shine through--as long as it’s through the framework of what I’m trying to do. There are conductors who try to mold everyone into their own image. I like a more collective approach,” he said. “The rest of it is hard work, basically.”

Sydney Symphony chief conductor Stuart Challender will lead the Pacific Symphony in music by Richard Mills, Rachmaninoff and Beethoven at 8 p.m. on Wednesday and Thursday at the Orange County Performing Arts Center, 600 Town Center Drive, in Costa Mesa. Soloist will be pianist Alexander Toradze. Tickets: $9-$52. Information: (714) 474-4233.