Argentina's Lionel Messi, cleared to play in the Olympics after striking a late deal with his club Barcelona, celebrated by scoring the opener and creating the winner as the South Americans beat Ivory Coast 2-1 on Thursday.
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Messi's participation in the Games had been in serious doubt after Court of Arbitration for Sport (CAS) ruled on Wednesday that Barcelona was not obliged to release him for the tournament.
But after a deal was struck over insurance cover for potential injury and a commitment that the forward would not play in international friendlies for one year, Messi took the field in Shanghai.
After a lively start from Ivory Coast, who played with plenty of pace and ambition, Argentina went close through forward Sergio Aguero who had a shot saved in the seventh minute and then blasted wide from a promising position 20 minutes later.
Ivory Coast forward Salaman Kalou had an effort disallowed for offside but Argentina were growing in confidence and fluency and after Riquelme had gone close with a free-kick, Messi found the breakthrough.
Riquelme threaded a superb pass into the path of Messi who showed great composure as he effortlessly slotted home.
The Africans fought back though after the break when Sekou Cisse rose superbly at the back post and his firm header flashed past Oscar Ustari to make it 1-1.
Messi, lively throughout, set up Aguero for a shot on goal that was ruled out for offside in the 65th and then with four minutes of normal time remaining he produced the inspiration for the winner.
Jinking in from the left, Messi fired in a low, diagonal drive which was parried out into the path of substitute Lautaro Acosta who slotted into the unguarded goal to ensure Argentina move top of Group A.
Rivals Australia and Serbia drew 1-1 earlier on Wednesday.