Footballers inside the ring: Man Utd legend Roy Keane went UNDEFEATED

To make it to the highest levels as a professional footballer, stamina, discipline and work ethic are essential attributes.

When combined with the kind of natural athleticism also seen in fighters, it is perhaps not surprising that, throughout the years, there have been crossovers from the pitch to the ring.

Wherever it is formative years spent in an amateur gym, a charity fight after retirement, or a full-blown career change, several footballers have tested their skills in the sweet science.

For better or worse these players stepped away from the protection of a team game, and challenged themselves in one of sport's most unforgiving avenues.

With the news that Wayne Rooney is debating stepping into the world of influencer boxing to sign with KSI's Misfits promotion, we took a look back at eight players who tried their hand at boxing.

Renowned as one of England's greatest-ever defensive talents, Rio Ferdinand enjoyed a glittering career across two decades as a professional footballer.

The centre-back twice broke the British transfer record, and upon arrival at Old Trafford in 2002 quickly established himself as one of the club's stalwarts in the latter years of Sir Alex Ferguson's all-conquering reign.

After more than a decade in Manchester, Ferdinand endured a decidedly less successful year at QPR before calling time on his career in 2015.

Although that retirement marked the end of his football career, Ferdinand's sporting ambitions found a new venture in professional boxing.

Aged 39, in 2017 Ferdinand announced he would transition to boxing with a documentary set to be filmed following his transition to a career in combat sports.

Less than a year after embarking on a training regime, Ferdinand was denied a license to box by