The string section of the National Philharmonic is spotlighted this weekend on Strathmore's stage under the leadership of Piotr Gajewski. Violist Victoria Chiang and National Symphony Orchestra Concert Master Nurit Bar-Josef team up to perform Mozart's "Sinfonia Concertante," one of the gems of the viola repertoire.

"The viola is a real specialty," said Chiang in reference to her instrument of choice in both professional performance and as a faculty member at Baltimore's Peabody Conservatory, where she serves as coordinator of the Viola Department. "There is the sound production and the size of the instrument, [both] very different from the violin. In a musical way, I was much more comfortable playing the inner voices [of the viola] and not being the standout person in charge."

Chiang leaves that honor to Ms. Bar-Josef, who made her solo debut with the NSO in February 2001 and joined the orchestra as the concert master seven months later. Her previous assignments were with the Boston Symphony Orchestra, the Boston Pops and the St. Louis Symphony.

"I'm so looking forward to working with her," Chiang said of her colleague. "I've never even met her and that's crazy, although we've emailed back and forth. It will be a new experience."

National Philharmonic Orchestra
Where: Strathmore, 5301 Tuckerman Lane, North Bethesda
When: 8 p.m. Saturday and 3 p.m. Sunday
Info: $28 to $81, children 7 to 17 free; 301-581-5100;

Not so with the "Sinfonia Concertante," a piece Chiang has played many times. She focuses each and every time on the challenges inherent in performing the music of the Austrian master composer.

"Mozart is difficult," she said. "His music requires absolute mastery and simplicity at the same time, and that's extremely difficult to do well. You can tell a great musician from the way they play Mozart. You have to have real ownership of everything -- your technical mastery but also your musical understanding." 

The evening’s program opens with Telemann’s “Concerto for Viola,” written around 1716-1721.

“Telemann was extremely prolific,” Chiang noted. “This is possibly the first concerto written for viola.  It’s fun and in four movements.”

 Closing the first half of the program is Mendelssohn’s “String Symphony No.9.”

As it is a symphony, there are no soloists in this sparkling and animated work that was influenced by the classicist Haydn. Mozart's "Sinfonia Concertante" closes the program and highlights charming exchanges between the orchestra, Bar-Josef and Chiang, who says with the anticipation of dining at a 5-star restaurant, "This is a feast for lovers of string concerti."