Machado was batting with Mark Reynolds on first and none out when he hit an 86-mph sinker on a 2-2 count from Royals starter Bruce Chen out to the opposite field, giving the O's an early two-run lead en route to a 5-3 victory over the Royals at Camden Yards.
"I didn't think it was going to go out," Machado said. "I thought it was going to bounce off the fence. I couldn't see the ball, so I couldn't really tell."
The ball appeared to bounce off the top of the wall and back onto the field of play. As Machado pulled into second base, Orioles manager Buck Showalter immediately came out to argue the call. After an umpires' conference and a look at the replay, it was eventually determined that the ball first made contact beyond the outfield wall, allowing Machado to trot home from second.
Machado's blast was his third in four Major League games -- all in this series -- and traveled an estimated 388 feet.
"He's going to be a good player for a long time, so we better get used to making good pitches to him," Chen said. "He definitely has the makeup and definitely has the ability."
Machado finished 1-for-4 on the day and is 6-for-16 with a double, a triple, three home runs, seven RBIs and four runs in his first four games.
By notching an extra-base hit in four consecutive games to begin his career, Machado matched a club record held by Ray Knight, Lee May and Frank Robinson.
"That's crazy, that's the first time I heard it," Machado said when informed of the record. "To be mentioned with Frank Robinson, that's just great. It's a great feeling. I'm just fortunate."
Greg Luca is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.