Focus

I really like the expressions you captured with this image, as well as the body language of the kid in red.  Nice!  I have only tried sports photography here and there, so I'm not so good at it.  However, one piece of advice I was given was to always try to move so as to get some sort of neutral background so that the figures on which you are focusing stand out.  That, and as narrow a depth of field as possible will help isolate your main subject(s).   It's all easier said than done, but that is what comes to mind when I see the background in this particular photo.  And...I'll look for the little guy in red with Barcelona of Manchester United in about 18 years!   Nice job!