Then when Craig Hill showed his pace with a 30 metre burst Richie Pugh was on hand to take the scoring pass to put Wales ahead by 10-0.
A strong run by Aled Brew then created the space for Wales' third try finished by Lee Beach who anticipated perfectly with great support, leaving the men in red shirts with a 15-0 interval advanatage.
Uruguay looked lively after the break and threatened with a dangerous run from Juan Martin Llovet, but a timely tap tackle from Craig Hill thwarted the south Americans.
Having defended their line Wales returned to the attack and were rewarded for good line-out work and crisp handling with a try in the corner by Richie Pugh.
Wales were reduced to six men after replacement Rhys Webb was yellow-carded for a high tackle. Uruguay took advantage of their extra numbers and came close to scoring only to held up over the line.
Against the odds it was six-man Wales who scored next after replacement James Merriman romped clear to score under the posts for a try converted by Lee Williams.
Wales now face top pool seeds Argentina in what should be a superb tie with Wales having a real chance of finishing top of their group.