When a perennial Tanglewood guest star like conductor Kurt Masur (from Leipzig's Gewandhaus Orchestra) teams up with a not-so-perennial star like pianistic Wunderkind Andre Watts, there are bound to be sizzling undercurrents of expectation - especially when they're playing an old chestnut like Beethoven's Fifth Piano Concerto.
The reputation of the German-trained Masur precedes him not only for his purist's sense of overall musical structure (sans affectation), but his savvy in communicating it to his players and audience. His skills were superbly evident in the first two selections of last Friday's program (one of five for Masur at Tanglewood this year): Mozart's ''Eine kleine Nachtmusik'' (K. 525) and Symphony No. 38 in D, K. 504.
Watts, on the other hand, is the quintessential firebrand, known for taking musical chances every time he flips his dress tails over the piano bench. He gambles both with tempo and phrasing, as well as his own supremely virtuosic skills.
The Watts-Masur melding produced a spare but steely ''Emperor'' this time around, conservative by Watts's standards, wonderfully free by Masur's. In a way , this is the perfect concerto for Watts, as the soloist takes the prerogative in introducing both development and recapitulation. Watts's flare for bravura erupted out of the shed and rippled across the lawn, packed with the largest crowd the Berkshires will see all summer at just over midpoint.
If Watts brought anything new to the performance, it was a more refined sense of dynamic shading - from the hushed pianissimos in the Adagio to thundering crescendos through the Rondo.
The crowd wanted Watts to play an encore, and Masur nodded, but Watts abruptly left the stage and sent listeners into the starry night elated - and wanting more.