The young right-hander was led to believe that he would start in Brazil's opener against Japan last week, but he ended up starting against another powerful squad in Cuba over the weekend.
In the end, Rienzo was tagged with the loss, but he was far from a disappointment as he held Cuba hitless over the first four innings. In fact, Rienzo had retired nine consecutive Cuba batters before a walk to lead off the fifth.
A single put runners on the corners and a groundout brought home Cuba's first run. After being removed because he met his pitch count at 65, Rienzo's other baserunner came home on a hit.
"Rienzo struggled with his control early, but then he was able to settle down," Brazil manager Barry Larkin told MLB.com. "He was kind of in a groove when he got to that 65-pitch limit."
After a long flight back from Japan to Arizona, Rienzo doesn't figure to get too much rest before returning to action in White Sox camp. After a solid minor league season in 2012, he will get more chances in person to show the White Sox's staff he is ready to pitch at the major league level sooner rather than later.
The 6-foot-3, 190-pounder, who can become the second native Brazilian to play in the big leagues after the Indians' Yan Gomes, was 3-0 with a 1.08 ERA at Single-A Winston-Salem last season, then went 4-3 with a 3.27 ERA in 13 starts at Double-A Birmingham. He also got one start at Triple-A Charlotte and pitched 6 2/3 scoreless innings.
From there he went to the Arizona Fall League and was in Venezuela for winter league.
The White Sox have multiple starting options beyond the five-man rotation with guys like Hector Santiago, Zach Stewart and Dylan Axelrod, but Rienzo could move ahead of those guys if he continues to do what he did on the big stage of the WBC.
"It's a great opportunity for me to be there and throw," Rienzo said before leaving camp for WBC play. "… I'm glad to have the opportunity."
As it turns out, it was an opportunity that wasn't wasted for the 24-year-old.