Atletico Madrid have taken a 1-0 lead into half time against Benfica, leaving them on course to win the group ahead of their Portuguese opponents.
After an opening which was fiercely contested yet lacking in goalmouth action, Atletico had the ball in the back of the net thanks to a header from Diego Godin, but the defender was correctly adjudged to have been offside.
As the opening quarter drew to a close, Atletico pushed forward again through Saul Niguez but his long-range effort was saved by goalkeeper Julio Cesar, before the Brazilian international was called into action to deny Gabi.
Benfica got back into the game well by beginning to dominate possession but shortly after the half-hour mark, Atletico went in front through Saul, who was on hand to provide the finish after being found by Luciano Vietto's cutback.
The home side's best chance of an equaliser fell to Renato Sanches, but after he fired wide, Atletico were able to take a narrow lead into the break.