The 31-year-old netted twice as Manchester City defeated bitter rivals Manchester United in the FA Cup final on Saturday.
In doing so, he secured the Sky Blues' second trophy of the campaign, and kept their treble dreams alive.
After climbing the famous Wembley steps, Gundogan was told there was no winners' medal left for him.
According to The Sun, Prince William told the Germany international they had ran out, meaning he hoisted the trophy without one.
Kevin de Bruyne is another star who was reportedly unable to collect his medal, before being passed one by goalkeeper Ederson.
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It has since been revealed that Gundogan, who is out of contract next month and continues to be linked with a move away, has been awarded with his personal prize.
On cup final day, teams are typically given 20 medals for their starting XI, substitutes and boss.
They are then given an extra 19 for all players and staff who had not received one, meaning Gundogan picked up a spare.
Gundogan's opener in 13 seconds was the fastest in FA Cup history, and he doubled his side's advantage after half-time.
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Bruno Fernandes had levelled from the penalty spot for Man United prior to the end of 45 minutes, before Gundogan won the match for City.
Pep Guardiola's side now have the opportunity to complete the treble, only something which has been achieved in the past by both Liverpool and Man United.
Man City take on Inter Milan in next weeks Champions League final, looking to get their hands on a first ever crown.