First Football shots

Just trying to get to get to grips with the 40D, these were shot yesterday at a local U16 match, with the 70-200 F4/L, using AI Servo, all focus points, high speed multi shot. No PP, simply conversion to JPEG in photoshop and cropped/resized.

I'd welcome any comments on the content and where I can improve my technique, as well as any PP that would improve the images. One thing I noticed myself is that you do need quite a high shutter speed to catch the action!

1.

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I like the third one best - good expressions on faces. I keep laughing at the second one - "what do we do now?". One, five and six are good action / portrait shots. Four looks like he's just kicking air - needs a ball in the picture.
Focus, exposure and cropping looks fine.