Barnsley under 18s returned to their dressing room after a 1-0 loss at Bristol City on Saturday to find that many of their personal items had been stolen.
The discovery came after they lost top-scorer George Maris early on to a wild Bristol tackle then conceded from a hotly-disputed penalty for an alleged handball by Harrison Biggins.
The weekend didn't get any better the following day when highly-rated left-back George Smith slipped on some mud while watching friends playing Sunday League football and suffered a collarbone injury which will put him out for the rest of the season.
Academy Mark Burton said: "It was a very bad weekend. The injuries are massive blows and it was disappointing to lose to a bad penalty decision. But being robbed was the worst thing. Thirteen iPhones were taken from the changing room as well as wallets, watches and driving licences.
"It was a case of total incompetence and unprofessionalism from Bristol City Football Club for not locking the changing rooms. Our academy manager Ronnie Branson is writing a report to the FA and the first team manager Danny Wilson was furious with Bristol City (his former club) when we told him. The lads had personal photos and videos on their phones which had sentimental value."
A Bristol City spokesperson told the Chronicle: "We apologise to Barnsley. "There has been a spate of burglaries in the Stoke Gifford area where the club's training ground is and unfortunately Barnsley's under 18s have been some of the victims."
Bristol's goal came from the penalty spot after Harrison Biggins was ruled to have handled the ball in the box. Burton said: "It was a bad mistake by the referee because it clearly hit his chest."
The young Reds remain second in the Professional Development League North and will complete their season with a match at home to Charlton tomorrow and a trip to Brighton on Wednesday. If they win both they will qualify for the end of season play-off semi-final against Queens Park Rangers. Barnsley under 21s completed their season with a 1-1 draw at Sheffield United on Monday. Brad Abbott got the goal.