"It's an exciting moment," said Souza, who will give the ball to his parents. "I just want to thank Jesus Christ, my Lord and Savior for putting me in this position and giving me an opportunity to come out here. It's an exciting moment for my family."
The 24-year-old, rated Washington's No. 14 prospect by MLB.com, earned his big league callup on Saturday when Denard Span went on the seven-day concussion disabled list. His hit came in his third at-bat since then.
A third-round pick in the 2007 First-Year Player Draft, Souza Jr. battled through several injuries and a 50-game suspension for testing positive for performance enhancing drugs in 2010.
"Everything that came together at this point," Souza Jr. said. "It's one of those things you've come so far and the hard work and the people that helped me along this way. It's a moment to share kinda with everyone.
"It's so cool, man. The love you get around here. The camaraderie. I'm just a new guy up here. Everybody is making me feel so welcome. To get hugs from [Ian Desmond], who I started with, to [Tyler Moore], one of my best friends. It's just a moment I'll never forget."
Christina De Nicola is a contributor to MLB.com. Teddy Cahill is a reporter for MLB.com. Follow him on Twitter at @tedcahill.