Atletico Madrid's Antoine Griezmann celebrates scoring
The French superstar won the 28th-minute spot-kick and then hauled himself up to convert it – but Marc Albrighton’s challenge that floored him was made outside the box.
It brought back bitter memories for Leicester fans of a certain age who still remember refereeing decisions costing them against Atletico back in 1997, when they were left reeling after having a player sent off and three penalty appeals turned down as they crashed out of the UEFA Cup to the Spanairds.
Ironically, Leicester had just started to trouble Atletico after hanging on for the opening 20 minutes, when they were rocked on their heels.
You could sense the home supporters starting to a get a touch restless as Leicester finally settled and began to mount attacks.
Manchester United fans react to Antoine Griezmann's performance against Leicester Wed, April 12, 2017
Manchester United fans are pretty excited on Twitter after seeing Antoine Griezmann's performance for Atletico Madrid against Leicester City in their Champions League quarter-final
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Manchester United fans react to Antoine Griezmann's display against Leicester
Shinji Okazaki was just inches away from getting his studs to Albrighton’s low cross which shot across the face of the Atletico goal. But minutes later Albrighton found himself in the thick of things for all the wrong reasons.
He chased after the fleet-footed Griezmann as he cut his way towards the edge of the box and the striker did not require any further encouragement the instant he felt connection and went sprawling to the turf.
Albrighton was horrified and booked for his protests as he argued that the contact was outside the area. But referee Jonas Eriksoon was having none of it and pointed straight to the spot to give the home side just the opportunity they were looking for.
Griezmann stepped up to take it, committed Kasper Schmeichel, who went to ground just as he sent it rising over him and into the net.
How it all came about was tough on Leicester though they can have few complaints at only going in at the interval a goal down. Griezmann caused no end of problems running from a deep role behind the main strikers and backed up by the shooting power of Koke, they threatened to cause chaos.
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Leicester City's Riyad Mahrez struggled
Koke had rattled Schmeichel’s left-hand post in the fifth minute with a powerful shot and then Yohan Benalouane had to move sharply to thorw his body in the way of another effort.
Atletico’s early movement was slick and incisive and the Foxes seemed to take a little time to get used to the speed of their play.
Griezmann so nearly made the breakthrough when he fed the ball through to Fernando Torres but the former Liverpool and Chelsea forward was falling backwards as he got his shot in and Schmeichel had little trouble collecting low down.
Griezmann chanced his arm with a 30-yard shot which brought gasps from the home crowd and Saul saw a similar effort from distance clear the visitors’ bar.
Leicester had to wait until the 55th minute of the game before registering their first real attempt on goal but Riyad Mahrez’s shot ended up going well over.
Craig Shakespeare will not be disheartened by his team's display
A few minutes later, Robert Huth was booked for sending Griezmann sprawling – a yellow card that means the defender misses the second leg at the King Power Stadium on April 18.
Then Mahrez tumbled theatrically in the box under a challenge by Gabi and was lucky not to see himself booked when clearly looking for a penalty.
Torres really should have made it 2-0 on the hour when he got himself into a great position just iunsdie the area only to slip at the crucial moment and end up ballooning the ball high and wide.
Defeat, then, for Leicester against overwhelming favourites for the tie. But a one-goal loss is far from a disaster and was exactly the margin from which they came back and dumped Sevilla out of the competition. Underestimate them at your peril.