The bout caught some heat from fans and pundits as being boring, but it was a bout in which both fighters had a lot to lose with a loss, neither is young and they have both lost, meaning the loser of this bout, really had to consider what to do after this bout.
The end came at 2:59 of the first after Ruiz arose from a knockdown.
The powerful southpaw hurt Ruiz with a straight left, and then followed up with a three-punch combination capped by a right hook to the side of Ruiz's face that dropped the challenger to a knee. His record now reaches 21-0.
The late substitute 32-year-old Ruiz was fighting for the second time in three weeks as he replaced the injured Abner Mares.
Ring Magazine reporter Ryan Songalia was quick to praise Davis on his destructive demolition.
This will be a huge step up for the hard-hitting Ruiz, even though 33 of his 39 wins are by KO, he will be at a size disadvantage going up to 130-pounds against a much larger and stronger Tank Davis.
'I was scheduled to fight Mares, but he had an injury. I'm very confident that I will be more active this year.
Mayweather is unsurprisingly keen to see Davis go to Asia having walked away from his bout with $10million (£7.7m) and while the 24-year-old is unlikely to get to such figures, he would make light work of the 20-year-old Japanese fighter.
Having swaggered to the ring to Michael Jackson's "Thriller", the American displayed his slick moves in the squared circle.
Mayweather mentioned Davis' crossover appeal because rap icons Drake, Lil' Wayne and Meek Mill and National Football League stars Odell Beckham Jr. and Antonio Brown were among those that composed the announced sellout crowd of 8,048 at Dignity Health Sports Park.