2) Mateo Kovacic, for Dinamo Zagreb, 17 years and 215 days
The Croatian is now at Inter Milan, and has been rumoured to be on the move to the Premier League with Manchester United, Arsenal, and Liverpool apparently among those interested. This first sign of his talent came in a 7-1 battering of his team by Lyon in 2011.
1) Peter Ofori-Quaye, for Olympiakos, 17 years and 195 days
Back in 1997 the Ghanaian put on in for the Greek side in a 5-1 thrashing by Rosenborg. He hasn’t shone since, and hasn’t even had a club since 2012. He had stints across the mediterranean and his home country before then.