The visitors, currently fifth in the Conmebol group, have numerous players one booking away from suspension against a side whose hopes of reaching Brazil are also in the balanceEdinson Cavani is among 11 Uruguay players who are one booking away from suspension ahead of their crucial fixture with Ecuador.
Oscar Tabarez's charges are locked in a tight battle in the South American World Cup 2014 qualification section, having finished fourth at the 2010 tournament in South Africa.
They currently hold fifth place in the Conmebol group with 22 points from 14 matches, while opponents Ecuador occupy the last automatic qualification spot but only lead Friday's visitors by virtue of goal difference
A loss for Uruguay would leave their top-four hopes in jeopardy, with a showdown against Argentina in Montevideo awaiting them in their final match.
They will draw confidence from their double-header against Peru and Colombia in September, though, which yielded a vital six points.
But they will be mindful of the fact that a whole host of players in their squad face the possibility of missing the Argentina match if they pick up another caution.
Paris Saint-Germain striker Cavani is joined by other experienced players such as Walter Gargano, Maxi Pereira and Gaston Ramirez in treading a fine line for the fixture in Quito.
Ecuador have six victories to their name but their hopes have been hit by their failure to win in their last four qualifiers.
Crucial to their hopes will be the form of Felipe Caicedo, who has six goals to his name in qualification so far while Manchester United winger Antonio Valencia is also included in the squad.