Yellow Coldplay Muting string

I am learning Yellow. I followed the video lesson from Justin, the song is quite easy, but I am in trouble in the first part.
You have to move your pinky finger down, and it is ok, but you have also to mute with finger 3 the 4th string.
This finger is busy pressing the 5th one, if I change the position of my hand I succeed to mute the 4th but also the 2nd.
Do you have any tips? I dunno if I need to change the position of my third finger.