Sporting Clube de Portugal gave Manchester City FC a chastening welcome back to Portuguese soil as Xandão secured a 1-0 first-leg victory against the Premier League leaders.
Drafted in to replace the injured Oguchi Onyewu, centre-back Xandão broke the deadlock with an inspired back-heel shortly after half-time. Triumphant after falling behind at FC Porto in the previous round, City were unable to turn their situation around this time and will require a more clinical edge at home next Thursday to reach the quarter-finals.
Stijn Schaars gave Roberto Mancini's men their first fright with an attempt from distance that sailed wide, but it was the more tangible blow of losing Vincent Kompany to a calf injury that disrupted their early rhythm. The damage was nearly compounded by João Pereira testing Joe Hart while Joleon Lescott was waiting to come on, and it took Kolo Touré's downward header from a James Milner cross to announce City's presence, Rui Patrício saving with his legs.
Gareth Barry then curled centimetres wide following a corner, but it was Sporting who had more purpose, and Matías Fernández threatened to strike after a jinking run close to the interval. Nigel de Jong blocked his effort, before Sergio Agüero had the last word of the half with a header clutched by Patrício.
If Sporting lacked a goal for their hard work, they corrected that flaw six minutes after the restart. Fernández's free-kick was parried by the sprawling Hart and the England goalkeeper then denied Xandão at point-blank range, but the defender was not finished yet and scooped a clever back-heel inside the near post.
Aleksandar Kolarov came close to levelling with a long-range shot that barely missed the target, yet City's determination to respond left them vulnerable at the back. Indeed, Ricky van Wolfswinkel perhaps ought to have scored after being fed by Emiliano Insúa in front of goal; instead, Hart gratefully snaffled the ball.
The game was opening up and Kolarov grazed the woodwork with a cross, before Agüero slid the ball wide from substitute Mario Balotelli's audacious centre. Balotelli then headed a corner against the bar and Xandão blocked a goalbound Agüero effort, but Sporting held onto their first-leg advantage.