Deftly juxtaposing the serious with the farcical and subtly blending sophisticated emotions and naive sentiments, Handel's Xerxes is an opera ahead of its time, one that anticipates Mozart's ironic, profoundly wise observations on human nature. Its score, one of the most imaginative from the composer who helped make Italianate vocal art all the rage in early-18th-century London, offers astute and vivid psychological portraits. Never mind that the plot, taken from an earlier Venetian hit, is a bit convoluted: Xerxes, king of Persia, falls in love with his brother's beloved, whose sister harbors an infatuation with the brother. The foreign princess betrothed to Xerxes and the king's attempt to build a bridge connecting Asia and Europe add to the complications. Handel gets plenty of mileage out of placing these solemn historical figures in comic situations--Xerxes, for instance, rhapsodizes about his fondness for a tree in a number now celebrated as Handel's "Largo"--yet he treats the wide range of emotions stirred up by love empathetically. This production, which originated at the English National Opera, boasts a number of local debuts, including mezzo Ann Murray in the trouser role of Xerxes and countertenor Christopher Robson as Arsamenes, his sibling rival. The staging by Nicholas Hytner, better known for his direction of Miss Saigon and the film The Madness of King George, transplants the action and personnel to Restoration England. The sure hands of John Nelson conduct. Friday, Tuesday, and next Friday, September 29, 7:30 PM, Civic Opera House, 20 N. Wacker; 332-2244.