Hearts were left to lament an appalling defensive lapse which blighted an assured performance in Germany and could yet curtail their UEFA Cup adventure.

Keeper Antti Niemi and striker Thomas Flogel left Krassimir Balakov's free-kick to each other as VfB Stuttgart secured an unconvincing victory in the first-round first-leg tie.

Flogel stood still on the goal-line as Balakov's curled shot arched over him, with Niemi - whom the Austrian believed would claim the ball - distraught at the mix-up.

If the pivotal moment was a preventable one, however, Hearts surely can atone in the second leg, given Stuttgart's inability to embellish their first-half lead.

But the visitors' controlled display was further marred by the loss of captain Colin Cameron, stretchered off in injury time and now doubtful for Sunday's SPL trip to Ibrox.

Stuttgart had seized the initiative instantly with Guinea international Pablo Thiam and Bulgarian veteran Balakov probing for spaces in a congested midfield area.

Both sides strung five players across the area, with Flogel and Sean Dundee the lone strikers. Dundee, born in South Africa but a naturalised German, hinted at the threat he would pose when he outjumped Steven Pressley in the third minute to set Balakov free on the left.

The 34-year-old's pinpoint centre found Jochen Seitz but, fortunately for the visitors, his sights were blurred and he headed woefully wide of Niemi's far post.

Niemi clutched another header in eight minutes, this time from Ahmed Salah Hosny, as the InterToto Cup winners hemmed Hearts into their own half.

The siege was lifted in 14 minutes, however, with Darren Jackson and Fitzroy Simpson both testing keeper Timo Hildebrand in quick succession.

Flogel broke on the right and, after Juanjo and Cameron supported, Simpson touched the ball into Jackson's path for a 20-yard shot which deflected into Hildebrand's arms.

The German Under-21 international was required to work harder to tip away Simpson's effort after a Jorg Albertz-style surge and shot which left Thiam trailing.

Grant Murray, moved to right-back by the return of Gordan Petric, extended a leg to deny Dundee as he charged towards Balakov's pass.

Hearts - backed by over 1,000 supporters in the crowd of 17,892 in the Gottlieb-Daimler Stadion - were coping well, with the return of Petric and Scott Severin offering additional security at the back.

Gary Locke had been declared unfit, while Gary McSwegan was considered only ready for a seat on the bench.

Hearts heaved a sigh of relief when Simpson, starting for only the second time this season, charged down a free-kick by Silvio Meissner in 30 minutes.

Right-back Meissner rampaged forward again in 34 minutes, with Petric's body-check leading to the free-kick from which Balakov scored.

Flogel retreated to the goal-line to defend the set-piece but, as Balakov swept a left-foot shot over the wall, it crept over the Austrian and under the bar.

The recriminations commenced immediately, with Flogel throwing his arms in the air in frustration and Niemi clearly upset by the costly misunderstanding.

Stuttgart were forced to withdraw the injured Jochen Endress two minutes later, substitute Thomas Schneider joining captain Zvonimir Soldo in central defence.

Dundee lashed the ball only inches wide after Thiam escaped Gary Naysmith in 42 minutes. Niemi then held an effort from Kristzian Lisztes.

Hearts resumed with Lee Makel on for Severin, who had suffered a recurrence of his ankle injury, with Petric soon to require treatment for a head knock.

Hildebrand held the ball under the bar in 58 minutes from Cameron - later replaced by Robbie Neilson - as Hearts sought the away goal which would have restored parity and proved handy for the return at Tynecastle a fortnight hence.

Juanjo's inviting cross in 60 minutes, after he turned away from Bradley Carnell, had no takers - but Stuttgart's anxiety was displayed as coach Ralf Rangnick urged his players to greater efforts.

Seitz was immediately replaced by winger Roberto Pinto after keeper Hildebrand had to race 30 yards from goal to concede a throw-in as Flogel threatened.

The change briefly galvanised the Bundesliga side and Hosny's fierce shot was blocked by Pressley. Hildebrand then held Juanjo's header at the other end.

Rangnick's frustration was transmitting to the Stuttgart supporters and also to Meissner, booked in 74 minutes for dissent.

McSwegan, who had injured an ankle in training on Tuesday, replaced Jackson three minutes later, with Flogel dropping deeper into midfield.

Stuttgart committed Romanian international striker Ioan Ganea for Dundee, with Simpson twice heading clear from Balakov corners as the Germans pressed.

Lisztes ripped a shot over Niemi's bar, before Petric's looping header was claimed under his bar by Hildebrand as Juanjo waited to punish any handling error.