Sporting Lisbon's Europa League campaign was left in tatters as their 10 men succumbed to Genk in Belgium.
Sporting led through Stijn Schaars' deflected opener on seven minutes, but there was little else for new boss Franky Vercauteren, who watched on in the stands, to be enthused by.
Benjamin De Ceulaer brought Genk level on 24 minutes and after Khalid Boulahrouz saw red after the break the ailing visitors conceded an 87th-minute winner to Elyaniv Barda.
The result means Sporting are rock bottom of Group G with just a draw from three games, leaving them six points adrift of leaders Genk.
Sporting announced former Genk boss Vercauteren as their new manager in the lead-up to their trip to Belgium in place of Ricardo Sa Pinto.
Vercauteren took on a watching brief, but he would have initially been content with what he saw as Sporting scored their first goal of the group stage after just seven minutes.
It came following a deflection as Schaars ambitiously attempted a volley from the edge of the area after Adrien Silva's corner perfectly picked him out.
Schaars did not hit his first-time effort cleanly, but Kristof Van Hout was left wrong-footed when the ball deflected off a defender in front of him.
Even then Kalidou Koulibaly should have done better on the back post, but the visitors cared not as they looked to kick-start their campaign.
Boulahrouz, who picked up his first caution after 12 minutes, narrowly headed a Schaars corner wide, but Sporting could only hold on to their lead for 17 minutes as De Ceulaer was allowed the freedom of the six-yard box to head in.
Julien Gorius fizzed in a corner and, when Anele Ngcongca got a touch, the ball found its way to the back post where De Cuelar was completely free to head home.
Sporting got to the break level on terms but their hopes of going on to grab a much-needed win took a hit when Boulahrouz was given his marching orders for a second yellow with 14 minutes left.
And their European campaign looked doomed when substitute Barda went unchecked as he headed in another Gorius corner at the near post.