Tip - Dog not playing nice

How do I stop my one year old pit bull from being so rough while playing with other dogs? He is a gentle dog but very strong and has drawn blood of another dog from simply playing. He likes to grab the saggy jowls of his boxer friend. He hasn't bitten people so far, however I would like to stop the biting altogether is that possible? Melissa Smith Norristown, PA Cesar Millan's Response