Lionel Messi emphasised his importance to Argentina, scoring one goal and setting up the winner as the south Americans kicked off their Olympic campaign with a 2-1 victory over the Ivory Coast.
Just hours after Barcelona confirmed they would allow Messi to remain in Beijing for the duration of the tournament, he showed his star power to inspire Argentina at the Shanghai Stadium.
Messi put Argentina ahead two minutes before the interval when he coolly sidefooted past Ivory Coast keeper Oscar Ustari.
However, the Ivory Coast threatened to spoil the party when they drew level eight minutes after the break through Sekou Cisse.
But the masterful Messi was not to be undone and just four minutes from time he squared the ball across the face of goal for Lautaro Acosta to tap home.
Host nation China opened their campaign with a 1-1 draw with New Zealand in front of 41,407 fans in the Shenyang Olympic Stadium.
But it took an equaliser two minutes from time to rescue a point as Fangzhuo Dong cancelled out Jeremy Brockie's 53rd-minute opener.
Cameroon drew 1-1 with Korea as another late goal, this time from Georges Mandjeck earned a point for Africans.
A strong Netherlands side was held to a 0-0 draw by Nigeria.
Earlier, Brazil were made to work for it but got their campaign off to a winning start with a 1-0 victory over nine-man Belgium at the Shenyang Olympic Stadium.
Belgium had Vincent Kompany sent off 20 minutes from time and Hernanes took full advantage to get the crucial goal after 79 minutes before Marouane Fellaini followed Kompany for an early shower.
Sebastien Giovinco was on target and two penalties from Giuseppe Rossi and Roberto Acquafresco gave Italy a 3-0 win over Honduras.
Stuart Holden's strike gave the United States a 1-0 win over Japan and Australia were held to a 1-1 draw by Serbia.