|Lionel Messi showed his best form of the tournament against the Costa Ricans, setting up two goals [Reuters]
Argentina shrugged off indifferent form in their first two matches to beat Costa Rica 3-0 in Cordoba and advance to the Copa America quarter-finals.
Sergio "Kun" Aguero opened the scoring in first-half stoppage time, and added a second just seven minutes into the second half of the match on Monday.
The 52nd minute goal came after Aguero was set up by a pass from Barcelona star Lionel Messi, who showed his best form of the tournament.
Angel di Maria, who plays his club football at Real Madrid, scored Argentina's third in the 64th minute, sealing a win that revives pre-tournament expectations that the hosts would challenge for the title.
Argentina now have five points from three matches, having drawn their previous two encounters, and finish second in Group A. Colombia won the group with seven points.
Aguero is now the leading scorer in the tournament so far, with three goals. Argentina, playing on home soil, are seeking to end an 18-year drought in major tournaments.
Under the Copa America format, the top two sides from each of the three groups advance, being joined by the best two third-place teams.
Argentina will now face either Chile, Peru or Uruguay in the quarter-finals, depending on who finishes second in Group C. Colombia will face the third-placed team from those countries.
Groups B and C will be settled on Tuesday and Wednesday. Costa Rica have still not been eliminated, despite Monday's loss, and await the outcome of other matches.
Argentina applied constant pressure in the first half, with Aguero breaking through just before the interval, slotting away a rebound past Costa Rica goalkeeper Leonel Moreira.
In the 52nd minute, he latched onto a through ball from Messi, tucking his shot inside the far post.
Messi set up the third goal, too, finding Di Maria, who slammed the ball into the back of the net from 15 yards out.
"I would like to thank Cordoba for the way you treated us, especially me,"Messi said afterwards.
"The truth is that we missed this affection, especially in the situation that we had arrived here in. Now it's another Copa (America) and we will do our best for Argentina."
Sergio Batista, the Argentina coach and former World Cup winner, fielded an attacking line-up, with Aguero, Gonzalo Higuain and Di Maria playing just in front of playmaker Messi.
Forwards Carlos Tevez and Ezequiel Lavezzi started on the bench, after having two poor matches in the tournament.
The new lineup looked far more settled, with Messi bossing the game as he has so far failed to do in the tournament.
Ricardo La Volpe, the Costa Rica coach, appeared to be playing for a draw from the start.
Costa Rica have been playing a young squad, composed largely of under-23 internationals, as they are a guest side in the tournament, and their senior side just finished playing the CONCACAF Gold Cup in the United States last month.