Mohegan — Based on The Who’s two-hour performance Friday in the Mohegan Sun Arena, and that whole “hope I die before I get old” thing, here’s an observation:

If you’re in your teens or even your 20s, and you have a rock band, beware. Say you’re rehearsing in your garage and the door blows open and 61-year-old Pete Townshend and 62-year-old Roger Daltrey walk in, borrow a guitar and a microphone, and break into “Won’t Get Fooled Again” or the “Tommy” medley they encored with Friday.

Your jaw will thud onto the floor, you’ll look at your spiral notebook with your stupid lyrics and predictable and puerile chord structures, you will crawl into a fetal position — and you will damned well think twice about whether you can be a rock star.

Yes, the surviving Who-sters can still bring it, thank you. With the sturdy help of a four-piece band and poignant, well-conceived and frequently humorous video montages, Daltrey and Townshend ignored the few ignobilities of age — Daltrey straining for a high note here, Townshend creakily shuffling between songs after some old-time calisthenics there — and took a capacity crowd on an amazing journey.

Townshend, in a loose, polka dot dress shirt, looked like a devilishly fun college lit professor who might have a dark streak — as when he threw his guitar at a roadie after a malfunction during “You Better You Bet.” His playing was superb and reminded all of why he’s the power chord king — and, yes, there were windmills aplenty.

Daltrey was sculpted, as though he runs a Work Out World franchise. His voice was more resonant with age but he nailed the scream in “Won’t Get Fooled Again.”

There wasn’t much interaction between the two except for a brief, awkward hug at the end, but they seemed to regard each other with amusement and respect. The set list was a mixture of anticipated hits and a large chuck of material from the just-out “Endless Wire” CD, including a six-song excerpt from that album’s mini-opera, “Wire and Glass.” Though the audience sat down for the recitation of the new stuff, they listened respectfully and, indeed, the tunes are impressively competitive.

There were no tunes from “Quadrophenia,” but “My Generation,” “Who Are You,” “Baba O’Reilly,” “I Can’t Explain,” “Generation” and the “Tommy” excerpts provided plenty of Big Moments.

In support, the Pretenders blew through a significantly great 50-minute set, reminding folks what a terrific band they still are. In a top hat and knee boots and armed with a litany of wonderful songs, Chrissie Hynde was the ultimate Mrs. Robinson-as-rock-queen fantasy.

r.koster@theday.com