Forget everything you know about Willie Nelson: the weed, the massive IRS bill, the resulting Taco Bell commercials, the weed, the solar powered tour bus, the Julio Iglesias duet, the reggae album, the weed. That’s all well and good, but what matters is the music. And the music of Willie Nelson is no joke. Nelson is an icon, an outlaw, a cowboy, a fierce guitar player and nuanced singer, a great songwriter, a larger than life character who seems hewn from a piece of granite. He is still out on the road most of the time at age 79, outperforming many people a quarter of his age. Nelson is, to use his own imagery, like an old grizzled matador who refuses to cede the ring because he knows he can still do battle and because it’s the only life he knows. A more apt comparison might be to that of a wily old boxer (like Philly icon Bernard Hopkins), who gets knocked down a lot, but always gets back up swinging and wins more than his share of fights. Nelson hasn’t stayed down on the mat or off the road long in his 72 years of performing, and he showed on Sunday night at the Keswick Theatre that he is still a champion. Nelson’s voice, while weathered, is still strong and memorable. His unique guitar playing – short staccato bursts of notes, with a strong Spanish/Classical influence – remains powerful as ever. Nelson and his crack band mixed classics, some deep cuts and a few recent songs to the delight of a packed house for almost two hours. The crowd listened carefully to the old master and between songs erupted in applause, letting Nelson know he was deeply revered and appreciated. Highlights: “Still is Still Moving To Me”, “Always On My Mind”, “Angel Flying Too Close To The Ground”, a medley of “Funny How Time Slips Away/Crazy/Nightlife” and late in the set a showstopper – a brilliant, epic “Ou Es-Tu, Mon Amour?/I Never Cared for You” (from 1998’s overlooked Teatro), showing that this gunslinger still has a lot of bullets left. — PETE TROSHAK