A golf fan had to spend a day in the hospital with a bloody head injury over the weekend ... and it's all 'cause Masters champ Hideki Matsuyama couldn't keep a drive straight.
Here's the deal ... Matsuyama was competing in the 2021 Shriners Children's Open in Las Vegas -- when on the 16th hole of his second round on Friday, he cranked a drive that went way right.
You can see in footage of the shot, it was so far from the fairway, it accidentally crash-landed into a fan's noggin -- knocking the guy to the ground.
Robert, the fan who was hit, tells TMZ Sports he was a bloody mess after the ball drilled him ... and felt "weird" and "totally disorientated."
I was standing next to this guy when he got hit in the head by Matsuyama’s 300 yard drive. He took it like a champ! Hideki signed a hat and glove for him. The guy told Hideki not to worry about it and continue playing golf. The medics arrived shortly after. pic.twitter.com/QxY6NS2cLG