Hamstring injuries are every young athlete's biggest nightmare.
Once you have problems with your hamstring, it can trouble you for the rest of your sporting life.
Real Madrid striker Michael Owen has always been plagued with injuries to his hamstring, and his former Liverpool team mate, Milan Baros, has also suffered.
They occur when you over-extend the muscle in the back of the leg.
Warming up properly is the best way to prevent this injury.
Sudden onset of pain or a pop in the thigh.
Rest, ice, elevation of leg and recovery program.
Within 2-4 weeks depending on severity. It can also recur for the rest of your sporting career unless it is properly dealt with.