SHANGHAI, China - The heat was on.

Having landed a spectacularly high-profile concert in the first week of Shanghai's Expo 2010 on Friday, the Philadelphia Orchestra and various partner organizations sweated bullets to get maximum mileage out of the situation, under the kind of inexplicably restrictive circumstances that prompt an oh-well-that's-China shrug.

To prepare for Friday's rehearsals, news conference, lavish reception, and concert - tailored for the expansive, architecturally spectacular Expo Culture Center - the orchestra's staff pulled all-night work sessions and improvised last-minute remedies for potentially fatal problems.

Example: When the musicians first rehearsed Rhapsody in Blue with pianist Stewart Goodyear, the reverberation in the stadium-sized venue was so great that they joked about hearing two versions - one second apart. Plus, the ventilation system drowned out the softer passages. Though the concert was a jumping-off point for any number of chances to promote Pennsylvania assets, from Drexel University to Hershey kisses, the music had to be there.

"A day of mystery" was how one musician described the complicated travel arrangements and mysterious security rules surrounding the events. Surprise was in there, too: Tuba player Carol Jantsch was drafted on 36 hours' notice to play at the Friday afternoon reception.

"It's like giving birth," said Craig Hamilton, vice president of community relations.

On the surface, though, each event maintained its smooth veneer, with the concert playing to a fully subscribed house of 4,500.

The backdrop for this final leg of the Philadelphia Orchestra's 2010 Tour of Asia was the almost unimaginable terrain of the Expo 2010 Shanghai. The world's fair, which opened May 1, is the latest of China's moves toward international outreach. The $58 billion infrastructure budget transformed derelict shipyards into a two-square-mile campus for 241 participating countries, among them Saudi Arabia, which spent $210 million on a bowl-shaped pavilion whose roof contains an oasis of palms and Bedouin tents.

Since most of the buildings will be demolished after the Expo's Oct. 31 closing, they're built for neither longevity nor winter weather, freeing their designers to be fancifully impractical in utterly different ways. Nepal chose to be charmingly archaic, while Israel went for a geodesic dome, though one that appears to have been inflated and looks like a giant balloon sculpture. Taiwan's diamond-shaped glass building encases a giant globe that turns vivid colors. If there's a common theme, it's small foundations supporting large structures that bloom outward and upward.

Attendance has been disappointing. Though early estimates forecast 380,000 visitors a day, attendance during the opening week was never reported higher than 147,000. Though Friday was sunny and pleasant, restaurants were often occupied solely by staffers.

But the Philadelphia Orchestra was assured a full house, since ticket allotments were given to each participating country and the rest to Expo-goers for free on a first-come basis. When a reporter complained during the Friday news conference that tickets were hard to get, festival officials lectured him that those willing to "do their homework" had gotten them.

That was just one example of how China's totalitarian attitudes have poked through the feel-good global unity implied by the Expo. Uniformed guards are everywhere, sometimes in the form of youth squads marching through the campus in formation. Others stand vigil in key parts of public spaces, sometimes on what resemble conductors' podiums, sheltered from the sun by giant beach umbrellas and surreptitiously texting with a free hand.

The orchestra had to share the stage Friday with performers from the China National Oriental Song and Dance Ensemble, who circulated through the Philadelphians wearing extravagant ethnic costumes. For scheduling reasons, the orchestra had been able to load in and set up only during the night. Security rules prohibit anything potentially menacing on campus, which meant that all musicians had to surrender instruments the night before the concert, right down to the piccolos. With so little time between setup and rehearsal, some orchestra staff camped out in the Culture Center's hallways for a bit of sleep.

The rehearsal was crucial. At the request of the Expo, the program was lightweight Americana - pieces by Gershwin, Copland, Bernstein, and Sousa that the orchestra knows well but hadn't played elsewhere on the tour, and thus needed to brush up on in the singular acoustic environment of the new arena. Players fanned out across an expansive oval stage, with the percussion section - a key part of "Mambo" from Bernstein's West Side Story - handsomely raised on a platform. Across the back, vertical video screens showed chief conductor Charles Dutoit, guest pianist Goodyear, and picturesque shots of Philadelphia's City Hall. Also on the program were works the Philadelphians have rarely played, such as the Chinese national anthem.

Clearly, the orchestra was at the center of a diplomatic mission, so much so that when Dutoit was complimented at the news conference for including Chinese music, his suave reply was, "Of course!" The orchestra's history with China, said chief executive officer Allison Vulgamore, predates its groundbreaking 1973 visit and goes back to wartime 1940, when it held a China-relief benefit concert. It also was noted repeatedly that the orchestra's principal cellist, Hai-Ye Ni, is from Shanghai.

(None of that, however, was much use to members of the Philadelphia Convention and Visitors Bureau, who had a visa snafu in Seoul, South Korea, that had to be hastily resolved between the Chinese national holiday on Monday and a Korean one on Wednesday.)

The promotional activities, including messages from Gov. Rendell and Secretary of State Hillary Rodham Clinton, were facilitated by the Pennsylvania Center, an organization that so successfully promotes the state's good points - from foreign-investment opportunities to educational institutions that draw overseas students - that at least one audience member walked into the concert venue asking to be directed to the "Pennsylvania Philharmonic."

And it's true that the Philadelphia Orchestra could've been mistaken for a lesser-known ensemble, given the way the Culture Center's amplification system leached the string section's famously lush sound.

But the ensemble played well. Goodyear put a stamp on Rhapsody in Blue that was both personal and had clear references to Gershwin's manner of playing. Dutoit revealed a seldom-tapped authority with lighter American music, even Sousa's "Stars and Stripes Forever," which brought down the house.

The concert's ultimate success, however, probably won't be measurable for years, and even then only anecdotally, when Philadelphia is no longer seen by Chinese businesspeople, investors, and tourists as a way station between New York and Washington.

At times, today's message from Philadelphia seemed to be, "You owe us."

As Hamilton diplomatically put it: "The Expo is the 'coming out' party for China. We were here in 1973 when nobody else was coming. And now we're still here."

Contact David Patrick Stearns at dstearns@phillynews.com.