IT was inevitable that attention would fall on the Uruguay bench last night given that Luis Suarez was named as a substitute, a further precaution following the striker's knee operation ahead of these finals. There he was found shifting uncomfortably but he was not alone - the sight of Costa Rica striding towards an unexpected 3-1 win was enough to cause the majority of his compatriots to squirm a little too.
The result was welcomed almost immediately as a boon for group rivals England. The scoreline might have raised a smile in Scotland too, with some supporters still able to recall with rancour a match in 1986 when the Uruguayans appeared reluctant to play fair - the most vivid recollection comprising the lunging tackle from Jose Batista on Gordon Strachan.
The Scotland manager is in Brazil this summer as a television pundit for the tournament and might have felt inclined to smile quietly to himself when he learned the score last night. He hobbled off in Mexico and this time the Uruguayans were given the equivalent of a dead leg as their campaign opened with an unsettling defeat.
Suarez's absence had given them cause for consternationa already and, on the evidence of this match, the Liverpool forward's arrival cannot come too soon for his country.
A penalty scored by Edinson Cavani midway through the first half - and won by Diego Lugano - had opened the scoring and put Uruguay into the lead. Yet the Paris Saint-Germain striker lacked both the energy and drive which Suarez possesses, and that became increasingly apparent as the match wore on.
Costa Rica seized their chance with two goals in eight minutes early in the second half to engineer an unexpected advantage in Group D. Arsenal's 21-year-old attacker Joel Campbell, who hit the headlines with a stunning strike against Manchester United in the Champions League while on loan at Olympiacos, and then Oscar Duarte did the damage as Suarez remained hunched on the bench.
Campbell then applied the coup de grace six minutes from time with a slide-rule pass which substitute Marcos Urena slid past goalkeeper Fernando Muslera from a narrow angle. That was Urena's first touch of the finals and it left a mark on his opponents.
Maxi Pereira appeared to seek retribution late on by taking a wild kick at Campbell - a challenge which would leave the Costa Rican prone on the turf.
It ended with Pereira trudging off when he was dismissed. The 30-year-old will now be absent from his country's match against England.
It remains to be seen, too, whether Suarez will feature in that game, although it seemed likely that the Liverpool striker was rested last night in an effort to ensure he would play in the rest of Uruguay's Group D fixtures.
He was both absent against Costa Rica and he was missed. Uruguay were made to pay for not providing their forwards with enough chances - Diego Forlan partnered Cavani up front initially - as Costa Rica turned the match around in four second-half minutes.
Cristian Gamboa's cross picked out Campbell 12 yards out and he hammered the ball unerringly past Muslera, who was also helpless to keep out a diving header by Duarte. The Costa Rican missed a glorious chance for an equaliser from a carbon-copy Bolanos free-kick move just moments earlier.
Suarez bristled at each goal, then sank back into his seat as his side were defeated. Urena added a third goal as Costa Rica left a mark on Group D.