Many have embraced the distinctive Oasis aesthetic, donning parkas and bucket hats in tribute to the band's enduring style.
Some even took it a step further by imitating Liam’s look completely.
Fans have come from far and wide to see their idols in Cardiff.
Huge sums of money have already been made from ticket sales alone. And this will be bolstered further when sales of merchandise are factored in.
Oasis are being supported in the UK by Richard Ashcroft, frontman of The Verve, and the Liverpool-formed band Cast.
Following their Cardiff shows, the band will perform at Wembley Stadium, Heaton Park, Murrayfield Stadium, Croke Park in Toronto as well tour United States, South Korea, Japan, Australia and South America.
Oasis fans sitting at tables having a drink outside a pub ahead of tonight’s reunion tour opener
No chance of any sunburn on the heads of these bucket hat wearing fans (Jordan Pettitt/PA)
Some fans went for a leisurely stroll around Cardiff city centre (Jordan Pettitt/PA)
Others took the opportunity to go shopping (Jordan Pettitt/PA)
A fan wearing a bucket hat with the band logo on it (Jordan Pettitt/PA)
A Liam Gallagher lookalike wearing sunglasses and a green parka (Jordan Pettitt/PA)
An Oasis fan from France poses for a photo outside the Principality Stadium (Jordan Pettitt/PA)
A fan from Argentina poses for a photo in front of an Oasis Live 25 sign (Jordan Pettitt/PA)
Oasis fans stand in the queue for the official merchandise stand outside the Principality Stadium in Cardiff (Jordan Pettitt/PA)
An Oasis fan holds a copy of the souvenir tour programme (Jordan Pettitt/PA)
Fans purchase merchandise from the official stand outside the Principality Stadium (Jordan Pettitt/PA)
Song title themed bucket hats on sale in the centre of Cardiff (Jordan Pettitt/PA)
Fans wearing merchandise from the band’s collaboration with Adidas (Jordan Pettitt/PA)
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