Bosnia Under-21 striker Anes Haurdic struck either side of the interval as Wales Under-21s were beaten.
Bosnia end unbeaten run of Flynn's men
Bosnia Under-21 striker Anes Haurdic struck either side of the interval as Wales Under-21s suffered a 2-1 defeat in Uefa Championship qualifying Group Three.
Brian Flynn's side suffered their first defeat of the campaign and must now wait 10 months for their next outing as they look to secure a play-off spot.
The visitors took an early lead through Swansea's Joe Allen, but goals in each half from Haurdic inflicted Wales' first defeat in their sixth qualifier.
Bosnia also missed a second-half penalty at the Grbavica Stadium in Sarajevo, and although Wales staged a desperate late charge they could not find an equaliser.
Now Wales must wait until September for the final games, away to Hungary and Italy, knowing they still need one victory to secure a top two finish in the group.
Cardiff youngster Adam Matthews won his first cap at this level, having been in the senior squad on Saturday which beat Scotland 3-0.
Captained
Matthews has been in impressive form for the Championship promotion-chasers this season, and he played at left-back in a side that included five full internationals.
Leicester's Andy King captained the side for the first time, with regular skipper Shaun MacDonald still struggling with a groin injury, although he was named on the bench.
Bosnia, previously without a win in the group, included just six of the players in their starting line-up that lost 2-0 to Wales in Wrexham last month.
But with Italy winning 4-0 in Luxembourg on Tuesday to close the gap on leading pair Wales and Hungary, the race to reach the 2011 finals in Denmark has intensified.
Wales, playing a 4-3-3 system with Simon Church, Sam Vokes and Ched Evans up front, were quickly into the attack, pinning the Bosnians back.
They got the perfect start with a fifth-minute goal from Allen, who fired home from 10 yards after Matthews' throw-in was flicked on into his path.
The Bosnian response was a sustained period of pressure and the home side were level after 29 minutes when a shot from Haurdic flew past Wrexham goalkeeper Chris Maxwell.
Pressure
The home pressure continued until the break, and Wales survived without any further mishaps.
Wales sent on Swansea's Ashley Richards at the break for the injured Matthews, and then introduced MacDonald for Vokes soon after the interval.
It meant that the Swansea winger, currently on loan at Yeovil, set a new caps record for the Wales under-21s with his 22nd appearance at this level, overtaking James Thomas, the former Swansea striker now playing in Australia.
Wales, though, were still under pressure and conceded a penalty when Darcy Blake was booked after 62 minutes for a foul on Haurdic.
But Wales received a major let-off when Nenad Kiso missed from the spot, firing his effort wide. However, their joy was short-lived when the outstanding Haurdic fired home his second of the match after 66 minutes to put Bosnia ahead.
It was now Wales' turn to try to mount a recovery, with Church, three times, Mark Bradley, Evans and Richards all going close as they searched for an equaliser, but to no avail.
