As if fighting Father Time isn’t hard enough for aging rockers, another nasty foe felled British legends the Who at Ford Amphitheatre Tuesday: bronchitis.

After less than a minute of the opening song I Can’t Explain, guitarist Pete Townshend waved off the band, the group fell silent and ailing singer Roger Daltrey, 63, promptly walked off the stage.

After a few minutes of discussion in the shadows — and with the crowd of 9,000 murmuring restrained dissent — Townshend returned to the stage and cancelled the show.

This was the first show the Who have cancelled like this in 40 years, according to Simon Townshend, Pete’s brother, who also plays in the band.

"I just talked to Roger and he can barely speak," 61-year-old Pete Townshend told the crowd. "I tried to get him to come out here, but he’s really, really sick."

Townshend said the cause was "bronchitis," although band officials did not confirm Daltrey’s malady.

Perhaps calming the masses, Townshend quickly announced that the show has been rescheduled for March 25 at Ford Amphitheatre. Tuesday’s tickets will be honored for that show. Refunds also will be available at point of purchase. Refunds will be granted until March 25.

As fans of the band wandered out of the venue, there were scattered boos and dejected harrumphs, but for the most part, the crowd was collectively understanding.

"Twenty five years ago, we would have had a riot," said Joe Backes, 45, a big Who fan from Spring Hill. "We’re older and more mellow now."

Formed 40-plus years ago, the Who, along with the Rolling Stones and the Beatles, helped spearhead the industry-shaking British Invasion. Ironically, as the band tried to play I Can’t Explain on Tuesday night, black-and-white images of the boys in their 1965 salad days flashed on a video screen behind them.

Go figure: The Who famously sang about hoping to "die before I get old." They never said anything about hoping for bronchitis.