Having already qualified for next summer's World Cup, Serbia travelled to Guangzhou for the warm-up match and Mitrovic made it seven goals in his last ten games for his country.
It was a simple close-range header from the big striker but is sure to boost his confidence ahead of the weekend's Premier League game against Manchester United.
Also on Friday, Freddie Woodman was an unused substitute for England under-21s as they beat Ukraine 2-0.
On Saturday, Ciaran Clark captained the Republic of Ireland as they drew 0-0 with Denmark. He was part of an impressive defensive display from Martin O'Neill's men in Copenhagen and that result means Tuesday's play-off second leg is perfectly poised.
Rob Elliot was on the bench but has now left the squad due to a family bereavement.
But while Clark and Elliot still harbour high hopes of a place in Russia, Chancel Mbemba's World Cup dream is over. the United defender played the full game as DR Congo beat Guinea 3-1, but that wasn't enough to see them qualify.