Tyson Fury declared "never say never" about joining WWE after playing a starring role at Clash at the Castle in the Cardiff.

The 34-year-old featured at the Principality Stadium on Saturday, joining in the headline clash between champion Roman Reigns and Drew McIntyre.

Fury left his front-row seat in Cardiff when Austin Theory attempted to cash in his 'money in the bank' contract before downing the 25-year-old.

Reigns emerged victorious by pinning McIntyre before the pair were greeted in the ring by Fury, who treated the crowd to a rendition of Don McLean's 'American Pie'.

While Fury waits for a heavyweight unification clash against Oleksandr Usyk, he refused to rule out moving to WWE after his boxing career comes to an end.

"At the moment I'm a heavyweight world champion, and I have plenty of fights I have to take care of over the next few years," Fury responded when asked about the prospect of joining WWE.

"But I really, really have a passion for WWE. Never say never."