Both sides brought contrasting group-stage fortunes into the clash in Santiago, with Chile unbeaten and netting 10 times en route to the quarters, while Oscar Tabarez's side - who had scored just twice - qualified through being one of the best third-placed teams.
Having won the competition a record 15 times, however, Uruguay brought with them the pedigree - and much of the pre-match talk had centered around their historical knack of eliminating the host nation from this tournament in previous campaigns.
Those omens did not seem as unnerving to Jorge Sampaoli's men as the visitors would have liked early on, with Chile starting much the better of both sides as Eduardo Vargas and Alexis Sanchez both fired warning shots inside the first 15 minutes.
Arsenal star Sanchez's influence grew as the minutes ticked on and the forward shot narrowly over the bar, before Arturo Vidal's 25-yard hit was punched clear by Fernando Muslera as the Chileans looked in full control but failed to make the most of their advantage before the break.
The second half began with the same tempo as its predecessor as Diego Rolan spurned a good chance to equalise, before Vidal's close-range header was kept out by Muslera - the latest incident in what was shaping up to be a personal duel between the pair.
Uruguay were then dealt a huge blow just after the hour mark when Edinson Cavani was shown a second yellow card for clashing with Gonzalo Jara off the ball, despite appearing to make very little contact with the defender.
Chile piled on the pressure after being handed the numerical advantage by the officials, but they were almost caught by surprise when Carlos Sanchez sent a volley inches wide of the post.
With no extra time being played in the tournament, the match looked to be heading for penalties until Chile finally made the breakthrough with eight minutes remaining, and it was Isla who clinched the win as he collected a pass from Jorge Valdivia before firing home the winner from the edge of the box.
After several flashpoints in the match, the frustration was clear late on as Uruguay were reduced to nine men when a second yellow card was shown to Jorge Fucile, who was also pulled away from the officials before Chile's victory was finally confirmed.