Boy, if I were to compete with you when I was also eleven, you'd be kicking my butt, cos this may be short but it takes nothing more than this to start on the way to becoming a great poet. Yes, I started at the age of 13, but not as close to being good as you are now at the age of 11.

"The fans in the stadium scream
cheering for their team
holding up banners
to support the players"

Here you caused me to think back to whenever I also play football in the presence of many people, the way they scream on top of their voices. So you painted a clear image there.

Critique:
Once again, although poetry could be without punctuation rules, but some times breaks are necessary to make the poems navigable.

So this is how I would have written this:
"The fans in the stadium scream,
cheering for their team,
holding up (their) banners
to support the players."

"the players are sweating
knowing they must try to win
keeping their anger inside them
they wait for the final whistle"

Good way to end it. The moment the game starts, the next thing on the mind of players is what they do before the final whistle. It would have been more interesting if you had continued with rhymes.

Nonetheless, a perfect poem. 5/5

First of all I love football. I'm like addicted to footbalt. Keep writing you will write great things. You are great :)