ANAHEIM — Robert Browning, the late-19th-Century poet who said "Grow old along with me, the best is yet to be," would have been less optimistic if he had been trying to make a living on the late-20th-Century pop-entertainment scene.

But country music, like the blues, is a pop sector where growing old is no crime. Together, George Jones, 60, and Conway Twitty, 58, have been walking the earth 20 years longer than the U.S. Senate delegation from their adoptive home state, Tennessee (Albert Gore is 43, James Sasser is 55). Jones, with his creases and wrinkles born of hard living, looks like the most care-worn Southerner since Jimmy Carter. And if Billy Graham ever needs a break, he might call on Twitty to stand in and provide that distinguished, graying-but-bushy-haired look at a revival meeting.

It's questionable whether the best is yet to be commercially for Jones and Twitty, each of whom has scored 63 Top Ten singles on the Billboard country charts. But their sold-out double bill Saturday night at the Celebrity Theatre showed that there are still plenty of fans willing to keep coming back as Jones and Twitty grow older.

Twitty's romantic ballads provoked appreciative shrieks from some of the women in the audience. A rich, grainy texture has settled into his voice without blunting its authority, making some of his songs sound more deeply expressive than on the original recordings.

Jones, though apologizing for a flu-diminished voice, had enough left to drive home a couple of ballads with the high, keening lamentation that is his trademark. Nor did the flu stop him from being a playful, if blarney-prone, host during his 50-minute opening set.

Twitty's hourlong performance carried some freight that can weigh on a country show: occasional Vegas-style posturing, and scrubbed, tinkling and whooshing synthesized keyboard sounds. But the overall conviction of his singing, and the focus on musical strengths rather than show biz glitter, rendered these problems as relatively minor.

The show bogged down once, during a ponderous, drama-milking version of the Bette Midler vehicle "The Rose." Twitty also went overboard at the end of a set-closing hymn, when he struck a prolonged pose under a spotlight that cut faintly through darkness, as if he were standing in the eye of God. But aside from that excess, Twitty made the song a convincing sinner's prayer for divine help.