Mendieta shakes off the attention of Stuttgart's Silvio Meissner

Holding a 2-1 lead going into the match, Boro were punished for their cautious approach after 13 minutes.

Stuttgart's Christian Tiffert made the aggregate scores level with a right-foot shot past Mark Schwarzer.

Boro needed some last-ditch defending to ensure their progress and will now face Roma in the next round.

In the first half, Middlesbrough showed little sign of the good form that had seen them achieve a four-game unbeaten run heading into the return leg, with Jimmy-Floyd Hasselbaink isolated in attack in a 4-5-1 formation.

Stuttgart, on the other hand, showed hunger and urgency from the off as they put Boro's back line under pressure.

Danijel Ljuboja, who scored the late goal to give Stuttgart hope in the first leg, brushed the side-netting with a curling free-kick from 20 yards in the opening 10 minutes.

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But it was Tiffert that put the tie back in the melting pot and levelled the scores on aggregate, using the outside of his right foot to slot the ball past keeper Schwarzer from just inside the penalty box.

Boro's first threat on goal came after 20 minutes - but Gaizka Mendieta's wayward free-kick failed to test visiting keeper Timo Hildebrand.

And while the hosts had a 10-minute spell midway through the first half when they began to pressurise Stuttgart, they looked lightweight in attack and second best on the night.

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Hasselbaink had a fantastic opportunity to give Boro breathing space straight from the re-start when Lee Cattermole's pass found the former Chelsea striker clean through on goal.

But, despite there being a strong hint of offside, Hasselbaink could only drill his shot at the body of the out-rushing Hildebrand, who kept alive Stuttgart's hopes.

Boro showed drastic improvement after the break as they managed to break through Stuttgart's high-lined defence only to be penalised for offside on two close-call occasions.

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Mendieta had a shot cleared off the line by former Liverpool defender Markus Babbel just after the hour mark, while Stuttgart were restricted to free-kicks dotted around the box, which were dealt with by Schwarzer.

Stuttgart made their intentions clear as the half drew on, throwing on attackers Cacau and Gomez.

But Boro's defence, which had conceded only one goal in their last four games, managed to contain the threat of their Bundesliga opposition.

Middlesbrough: Schwarzer, Davies, Riggott, Southgate, Queudrue, Parnaby, Cattermole, Mendieta (Ehiogu 86), Boateng, Downing (Taylor 90), Hasselbaink (Yakubu 86).
Subs Not Used: Jones, Maccarone, McMahon, Viduka.

Booked: Boateng, Mendieta, Cattermole.

VfB Stuttgart: Hildebrand, Hinkel, Babbel, Delpierre, Magnin (Hitzlsperger 80), Soldo, Tiffert, Meissner (Cacau 75), Gentner, Gronkjaer (Gomez 64), Ljuboja.
Subs Not Used: Heinen, Gerber, Carevic, Beck.

Booked: Tiffert.

Goals: Tiffert 13.

Agg (2-2)