We're having a dinner party next week, and I'm getting a bit nervous, as I have discovered that one of the guests is a wine connoisseur. I don't want to embarrass myself, but I simply can't afford to spend $50 or $100 for a bottle of wine that will be acceptable. My maximum is more like $20 to $30. The menu is shrimp salad for the appetizer, and roast lamb for the main course. Can you recommend a good wine for the occasion?

Relax. The solution to the wine expert coming to dinner problem is simple: Surprise and delight the expert with a wine with which he or she is unfamiliar. That's a lot easier than you might think.

Most wine connoisseurs are "power users." Like the computer geeks who have to have the latest Intel chip or graphics card, wine connoisseurs usually focus on a just a few must-have wines to the exclusion of others. Typically, these are vintage wines that have received mega-ratings, such as 95 points out of a possible 100, from the major wine publications. Such wines tend to be from a few high-profile areas that are intensely covered by the wine media, particularly in the best vintages. Most are made from classic French grape varieties, such as cabernet sauvignon, merlot and pinot noir. Major examples include Napa Valley cabernets, classified growth Bordeaux, red and white Burgundy, red Rhones, Italian Barolo and Barbaresco, and boutique wines from elsewhere. A price of $50 to $100 is not unusual for such wines.

Fortunately, many exceptional wines do not fit into these ritzy categories. As a result, many aficionados never taste them and know shockingly little about them. If you want to impress your guests and come in under budget, this is where you need to be.

A prime choice is the impressive Stags' Leap Winery 2002 Petite Sirah ($32; California; Washington Wholesale), which is just right for roast lamb. Big, lush and richly fruity, this deep black, blueberry-scented wine offers startling depth and dimension of flavor. Because it's made from the petite sirah grape, an obscure variety often confused with the ubiquitous syrah, it is thoroughly undervalued. A Stags Leap district cabernet sauvignon of this quality would command a price tag of $50 to $80. If $30 to $35 is too high, look for petite sirah from Foppiano Vineyards or Guenoc, which specialize in this varietal. The gutsy Foppiano Vineyards Petite Sirah Russian River Valley "Bacigalupi Vineyard" 2001/2002/2003 ($18-$20) dishes out copious amounts lot of delectable black and red berry fruit. Guenoc Petite Sirah North Coast 2001/2002 ($15-17) is a bit less powerful than Foppiano, but is also a fine match with lamb or beef.

Another compelling choice for the red is Perrin & Fils 2002 Perrin "Les Sinards" Chateauneuf-du-Pape ($30; NDC; France). If your guest remarks that this is reminiscent of the $80 Chateau de Beaucastel, the guest should get a gold star. That's precisely what this is. In 2002, torrential rains drenched southern France, wreaking havoc in the vineyards. Chateau de Beaucastel elected to declassify its entire production and bottle it under the Perrin & Fils "Les Sinards" label, because it decided the aging ability was not up to snuff for the grand vin, due to a less tannic structure. But that doesn't matter if you are serving it next week. Though less concentrated than in its best years, this luxurious wine has all the class one would expect of a Beaucastel in a ready-to-drink style.

Because the 2002 vintage has a bad reputation, other 2002 Chateauneuf-du-Papes will be similarly ignored by wine aficionados. Price-cutting has already commenced, with some big-name wines priced as low as $20 to $25. Chateauneuf-du-Papes to look for include Andre Brunel (Kacher Selections), Chateau de la Nerthe (Clicquot), Domaine de la Mordoree (Kysela), and Clos des Papes (Junguenet). Note, however, that because many retailers passed on this unfashionable vintage, availability will be spotty. It's prudent to telephone the stores before heading out, or check the ads in the newspaper or online for bargains.

For a white wine to go with the shrimp salad, I recommend a dry Alsace riesling. The French region of Alsace, which borders Germany, can confound anybody, including knowledgeable wine lovers. The bottles look German, and the grape varieties are the same as in Germany. However, unlike German riesling, which is usually sweet, Alsace riesling is typically dry. An effort was made to make the region easier to comprehend by designating the best vineyards as grands crus, as in Burgundy, but it was botched, by omitting several deserving vineyards and including a few subpar sites. Several top producers declined to apply for grand cru designation, further compounding the confusion.

Whether designated as grand cru or not, Alsace riesling might be the most complex dry white wine in the world that is obtainable for less than $20. There are many excellent producers. Ones to look for include Trimbach, Pierre Sparr, Hugel, Lucien Albrecht, Albert Mann, Rene Barth, Paul Blanck, Mure, Marc Kreydenweiss and Domaine Weinbach. Although Alsace has had a string of good vintages since 1999, with dry riesling I recommend drinking the youngest available vintages: 2001, 2002 or 2003.

You don't mention dessert, but the way to finish with a crescendo is a "sticky," the Australian word for a luscious sweet wine. The Peter Lehmann Botrytis Semillon Barossa Valley 2001/2002 ($17; Australia) is similar to a Barsac, with moderate sweetness and good acidity for a fresh palate impression. It's a splendid match with poached pears, lemon spongecake and fresh fruit.