Villarreal proved too good for Swansea as the Spanish outfit claimed a 3-0 win at the Liberty Stadium.
Swansea boss Garry Monk named a near full strength line-up, but they were no match for the in-form Yellow Submarines.
The game started poorly for Swansea with Ikechukwu Uche putting Villarreal ahead after just three-minutes.
Swansea improved but they could not find an equaliser, and Villarreal added two further goals after the break.
Captain Bruno Soriano curled home the second before substitute Denis Cheryshev headed home from close-range.
Swansea are now gearing up for their opening Premier League fixture - which for the second season in-a-row sees them take on Manchester United.