In a strange game played at the Estadio Do Dragao Porto and Roma played to a 1-1 draw that leaves things nicely poised going into the second leg.
Roma went ahead in the 21st minute courtesy of an own goal from Porto's Brazilian defender Felipe but things took a turn for the worse before the break when new recruit Thomas Vermaelen was sent off on debut.
The Italians tried to hold on with just ten men but were eventually undone when Andre Silva netted from the spot just past the hour mark.
Meanwhile Monaco travelled to Spain to take on Villareal and came away from the encounter with a 2-1 win.
The French side were up within minutes as Fabinho converted a penalty but Brazilian compatriot Alexandre Pato marked his debut with the equaliser.
After the break it was Monaco who again broke the deadlock with substitute Bernado Silva scoring in the 72nd minute and despite going down to ten men late on they held onto their lead.
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