Here's tennis star Genie Bouchard in a butt-baring bikini on the beaches of Spain ... blessing all our senses while teaching the common man a lesson ... luck has its limits.

Eugenie just got bounced from the Mallorca Open -- so she hit the sand with her hockey player boyfriend, Jordan Caron.

You know who WASN'T invited? The lucky schmo Genie went on a date with after the infamous Super Bowl bet -- a bet in which Genie agreed to go out with the guy if the Pats came back from that 28-3 deficit.

They did and Genie let the guy (John) take her to a Nets game. Later that night, TMZ Sports got Bouchard saying that date #2 was in the cards -- but that clearly didn't pan out 'cause she's on the beach with Mr. Hardbody.

Tough break for John. Good for Caron. Even better for butt enthusiasts.