Cavan Sullivan is emerging as one of the United States’ most promising young footballers after becoming the country’s fourth-youngest international at 16 years and 363 days. The Philadelphia Union midfielder started in a 4-1 friendly win over Peru and is attracting attention ahead of his planned move to Manchester City, although expectations are being tempered because he is still only 16.

Sullivan has seven MLS goals and five assists this season, with six goals and four assists coming in August and September. He has scored six times in his past six matches and earned seven Team of the Matchday selections, helping Philadelphia go unbeaten in 11 games after a poor start; experts nevertheless warn that previous American prodigies, including Freddy Adu and Gio Reyna, show that early promise does not guarantee elite success.