Jonathan Edwards scored the first goal of the under 18s tour in Exeter, but it was not enough to earn victory.
The Peterborough United under 18s are spending three days in Exeter ahead of the new campaign and began their short stay in the West Country with a 2-1 defeat against a strong Royal Marines Football Association X1.
Striker Jonathan Edwards, who ended last term in fine form, opened the scoring for the youngsters in the second half with a well-taken strike from just inside the box, firing into the top corner after holding off the attentions of the Marines' centre back.
Dave Robertson's men had plenty of opportunities to extend that advantage with Jack Friend, Robert Duggan and Ty Phillips all going close.
They were made to rue those misses when the Marines, whose side were packed with experience, as well as age, levelled the scores with a close-range header.
Two minutes from time, the hosts completed the turnaround with a tap in after Henrich Ravas had saved the initial effort from the edge of the box.
Posh face Exeter City on Wednesday morning with the players completing a morning training session on Tuesday followed by a visit to the local barracks.
Posh squad involved: Ravas, Marshall, Goode, Luto, Ward, Duggan, Maslen-Jones, Adebayo-Rowling, Friend, H.Anderson, Edwards, Robinson, Phillips, Hood, Humphrey, Conte, Henry.