UEL Semi-finals, First Leg

28 April 2011
Porto – Villarreal
Referee: Björn Kuipers (NED, photo)
Assistant Referee 1: Sander van Roekel (NED)
Assistant Referee 2: Berry Simons (NED)
Additional AR 1: Richard Liesveld (NED)
Additional AR 2: Ed Janssen (NED)
Fourth Official: Pol van Boekel (NED)

Benfica – Braga
Referee: Craig Thomson (SCO)
Assistant Referee 1: Francis Andrews (SCO)
Assistant Referee 2: Graham Chambers (SCO)
Additional AR 1: Alan Muir (SCO)
Additional AR 2: Calum Murray (SCO)
Fourth Official: Robert Madden (SCO)