Spain's young footballers showed why they are favoured to win the Under-20 World Cup by beating the United States 4-1 on Friday after doubles from star strikers Jese and Gerard Deulofeu.
France also turned in a strong performance in the other Group A match in Istanbul, scoring two second-half goals within four minutes to win 3-1 against Ghana.
Security has been stepped up at all seven sites following weeks of sometimes violent protests after riot police cracked down on environmental activists who opposed plans to remove trees and develop Gezi Park in Istanbul.
But the protests this week have given way to peaceful resistance and there were no signs of protesters on Friday at the Ali Sami Yen Arena.
Instead, the problem was a lack of spectators with only 2,800 fans, leaving much of the 50,000-seat stadium empty.
That confirmed FIFA's fears ahead of the tournament that tickets were selling too slowly, with only 300,000 of the 1.3 million tickets sold.
Meanwhile, in Group B matches at Kayseri, South Korea came from a goal down to beat tournament newcomers Cuba 2-1 and Portugal downed Nigeria 3-2.
Information from the Press Association was used in this report.