The Blues wing-back appeared to stand on the back of Southampton forward Long's calf.
GETTYMarcos Alonso helped Chelsea recover against Southampton
Chelsea came from two goals down to win 3-2, with all three goals coming in an eight-minute span in the second half.
Klay Thompson sets Spurs ablaze in Game 2 win
But Thompson answered with a bucket from the corner with 2.3 seconds remaining, making it a six-point game at intermission. Even with a high-powered offense at their disposal, Golden State was able to take Game 1 with their suffocating defense.
Marcos Alonso of Chelsea gives his team instructions during the Premier League match between Southampton and Chelsea at St Mary's Stadium on April 14, 2018 in Southampton, England. For retrospective action to be taken the decision of the panel must be unanimous.
The Blues are now seven points behind rivals Tottenham, who play Brighton on Tuesday evening, and their remaining Premier League fixtures are against Burnley, Swansea, Liverpool, Huddersfield and Newcastle.
DC Finds HARLEY QUINN/BIRDS OF PREY Director
This is a bold bet for Warner Bros' Geoff Johns and Walter Hamada, who oversee DC under Toby Emmerich. She is still negotiating to star with Leo DiCaprio and Brad Pitt in Once Upon a Time in Hollywood .
Alonso has until 6pm on Wednesday to respond to the charge.
Alonso's challenge was missed by referee Mike Dean on the south coast, and was only spoken to during the Premier League victory over Mark Hughes' relegation-threatened side. "They were all within a 10 to 15 metre radius - one of them should have seen it".
Sun, Rain and Snow; Three Days of Weather!
Saskatchewanians might need to pull their snow shovels back out thanks to a fresh dusting expected to fall on Tuesday . Lots of cloud cover and strong cold winds will keep all the light snow cover on the ground at least through Tuesday .