Darwin Núñez headed home a 77th-minute winner as Benfica grabbed a shock 1-0 victory at Ajax on Tuesday to secure a surprise Champions League quarter-final place. The Uruguayan striker rose above the Ajax defence to score from a free-kick in a rare attack for the Portuguese club, who put up a stout defensive performance at the Johan Cruyff Arena to advance 3-2 on aggregate. Benfica’s veteran centre back pair of Jan Vertonghen and Nicolás Otamendi were a defensive wall that Ajax were unable to break down, despite dominating possession and constantly attacking the visitors’ goal. The Dutch club had won all their group games and, after a 2-2 draw in the first leg of the last-16 tie in Lisbon last month, were expected to ease through to the last eight with home advantage in the second leg. But their hopes of an extended run in the Champions League were brought to a sudden end by Benfica, who have had a poor domestic season and flounder 12 points from the summit of the Portuguese league. Ajax peppered the Benfica goal in the first half at the end of swift build-ups and multiple crosses into the penalty area, but got few of their efforts on target. Ryan Gravenberch created an opening for himself with a strong run but the 19-year-old fired his 36th-minute shot just over the bar in the best effort of the opening period. Ajax kept up the pressure in the second half with Brazilian winger Antony having two good chances. He put a header wide and was then foiled by a late Vertonghen tackle. Benfica’s one attempt on target came after the Ajax defender Edson Álvarez conceded a soft free-kick. Núñez rose high above Jurrien Timber and the onrushing goalkeeper Andre Onana from the set piece to stun the home crowd. Ajax looked to be set to equalise deep in stoppage time but the Benfica goalkeeper Odysseas Vlachodimos pulled off a superb stop to deny Brian Brobbey and the Ajax substitute was then ruled offside.