Eden Hazard put Chelsea into the lead against Crystal Palace just before half-time.
The Belgian, Chelsea's star player this season and the PFA Player of the Year, didn't seem to get a lot of contact from Palace midfielder James McArthur before falling to the ground.
Hazard stepped up to take the penalty himself and although his weak effort was saved by Julian Speronio, Hazard was able to nod home the rebound and move Chelsea to just 45 minutes away from winning the title for the first time since 2010.
But was it a penalty?
Speaking at half-time, Sky Sports pundits Thierry Henry and Jamie Carragher didn't think so - although former Arsenal striker Henry said that Hazard was "clever" to get the contact.
"At full speed, we all thought it was a penalty and it is difficult for the referee not to give it," said the Frenchman. "But Hazard is clever. He's off balance and he's looking for contact.
"You have to give him credit. He went there, forced it and got his reward. I think it was a penalty, yes."
Former Liverpool defender Carragher added: "I think the two knees clash, MacArthur and Hazard. You say he's looking for it, I don't think so. The two knees clash and it's a penalty."
However, the pair also said that Chelsea should have conceded a penalty earlier in the half, when skipper John Terry blocked a Jason Puncheon shot with his arm.
"He's fortunate that it takes a deflection off Azpilicueta but Terry's great at this - making himself big," said Carragher.
"He always makes himself big, making sure you can't pass him in some way," said Henry. "He did it again this time and got away with it."
Chelsea went on to win 1-0 and secure their first title since doing the double under Carlo Ancelotti in 2010.
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