Southampton came from a goal down to beat Inter Milan by two goals to one, thanks to a goal from Virgil Van Dijk and a Yuto Nagatomo own goal.
Mauro Icardi scored in the 33rd minute, when Inter broke against the run of play and the Argentinian was left unmarked to fire home.
It could have been an even bigger margin of victory if Dusan Tadic's penalty hadn't been saved by Samir Handanovic. The Saints were awarded the dubious spot kick after the ball appeared to bounce off the hand of Ivan Perisic.
Van Dijk scored just after the hour mark after the ball cannoned off the bar. Nagatomo then put the ball into his own net five minutes later.
The win means Southampton remain second in the group.
First half sparks into life
The first half was a poor showing and didn't really come to life until just after the half hour mark. Antonio Candreva broke down the right hand side and squared the ball for Perisic, who's shot was blocked by Martina twice. However, Mauro Icardi was there to cleverly fire home to rebound against the run of play.
Southampton, however, continued to dominate possesion and their reward nearly came on the stroke of half time.
A corner was whipped in by Tadic and when Inter couldn't clear their lines properly, the ball fell to Hojbjerg who stroked it off the hand of Perisic. The decision was a harsh one and the fact that Tadic missed it probably evens it up. Handanovic has now saved the last three penalties fired at him in this season's competition.
Before the penalty was taken, Candreva was lucky not to receive a straight red card from the referee. The Italian was seen scuffing the penalty spot before Tadic stepped up to take his attempt. When youngster Sam McQueen went to stop him, he received an elbow straight to the face.
The referee was metres away and ran over the sort the situation immediately. Somehow, Candreva was only shown a yellow card.
Inspired Saints comeback
Southampton looked even more hungry after the interval. James Ward-Prowse fired two fantastic efforts towards the Inter goal but both were smartly saved.
Van Dijk went down twice in the penalty area after being held by Andrea Ranocchia. Both appeals were waved away. However, Van Dijk got his revenge, when Inter failed to clear a corner, the ball fell to Oriel Romeu who looped his shot onto the bar and Van Dijk was there to smash home from six yards out.
It got even better for the Saints just five minutes later. Tadic attacked down the left and his low cross could only be turned into Inter's goal by the Japanese left back Nagatomo.
Southampton kept pushing for a third goal and they nearly got it late on. Nathan Redmond had two chances. His first was a glancing header and his second was a low driven shot that went just wide of Handanovic's goal.
Icardi tried his luck from range late on but Fraser Forster was on hand to parry the shot away from goal.
The well deserved win means Southampton remain second in the group and Inter remain rooted to the bottom.