When AC/DC announced last month that singer Brian Johnson would not be able to continue touring with the band, their fans were upset. When they announced a few weeks later that Axl Rose, 54, infamous lead vocalist of Guns 'n' Roses, fans were downright afraid of what would happen to the AC/DC they had known and loved since Johnson replaced Bon Scott in 1980.

Those fears were assuaged Saturday night in Lisbon, Portugal when the reformed band took to the stage for the first time.

Overall, fans impressed by first performance

While Rolling Stone's Mark Sutherland said Rose seemed a bit unrehearsed, he noted the particular ease in which the veteran singer was able to perform the band's biggest hits, originally sung by the late Bon Scott.

Sky Media reported that fans from throughout Europe turned up in Lisbon for the event and most were blown away by Rose's performance:

"You couldn't even tell the difference in the vocals," said one Portuguese fan.

"Axl Rose has a lot of respect for the group," said Paulo Dias, another local fan of both bands, adding," he has the voice for it."

AC/DC, Axl both victims of terrible luck

AC/DC has been a band plagued with a bout of unfortunate luck in recent years.

During an earlier leg of the band's "Rock or Bust" tour it was announced singer Brian Johnson had been suffering from hearing loss for due to years of performing with the band, as well as racing cars.

In March, a string of twenty gigs had to be postponed due to Johnson's condition and eventually he was told by doctors that he needed to stop performing in order to save what was left of his hearing. In September 2014, guitarist and band co-founder Malcolm Young was forced to "retire permanently" at the age of 61 due to a dementia diagnosis.

At the time, a source close to the band told the Sydney Herald that Young had been moved to a nursing home specializing in dementia support. In 2015, the band's 5th and 7th drummer Phil Rudd was convicted of "threatening to kill" and drug possession in New Zealand. He was re-arrested later that summer for violatinghis eight-month house arrest.

On April 8, Axl Rose revealed via social media that he had broken his foot during a Guns 'n' Roses warm-up show in Los Angeles. Due to the injury, he sat through most of AC/DC's set in Lisbon Saturday night. Rose has another 9 shows to go on the AC/DC tour before hitting the road for the summerfor aGuns 'n' Roses reunion. It is unclear at this point how much longer he will be forced to perform in a leg cast.