Spoiler: surprising WWE Superstar returns to SmackDown to accept LA Knight's United States Championship open challenge

WWE Superstar LA Knight defended his United States Championship in an Open Challenge in the first match tonight on SmackDown. A star from RAW answered the challenge on tonight's edition of the blue brand and battled The Megastar for the title.

Imperium's Ludwig Kaiser accepted the open challenge for the United States Championship tonight. His stablemate, World Heavyweight Champion Gunther, will be defending the title against Randy Orton at WWE Bash in Berlin tomorrow night. Kaiser got a huge pop from the crowd and controlled the action early.

He sent the United States Champion into the steel steps and hit him with a dropkick as SmackDown went to a commercial break. When WWE SmackDown returned, Kaiser was still in control of the action, but Knight battled back. The crowd in Berlin was fully behind the Imperium member and broke out in a loud "Ludwig Kaiser!" chant.

The action spilled out of the ring and LA Knight bounced Kaiser's face off of the announce table several times. Back in the ring, Knight connected with a neckbreaker and then an Elbow Drop off the middle turnbuckle for a near fall. LA Knight then followed it up with the Blunt Force Trauma to retain the United States Championship via pinfall.