Given an unexpected chance, the Rays left-hander made the most of the opportunity on Sunday.
Romero combined with five relievers on a three-hitter in his major league debut, leading Tampa Bay over the Baltimore Orioles 3-1.
Tampa Bay remained a half-game ahead of Cleveland in the AL wild-card race, and Texas dropped 1 games behind the Indians for the second berth.
"Enny just shows up after he tweets that he belongs here ... so we actually read twitter," Rays manager Joe Maddon said with a smile. "For all our minor leaguers out there, get on twitter and you might end up in the big leagues for the playoff run. It's fun to watch that we can bring up somebody from the minor leagues, under these circumstances, against a very good team, and get that kind of result."
Tampa Bay beat Baltimore for the third time in the four-game series. The Orioles fell 4 games behind Cleveland.
"We'll have to get little cooperation mathematically, but you'd be surprised how quickly the outlook on things change in one day's time," Baltimore manager Buck Showalter said.
Dating to the final 11 innings of the Rays' 5-4 victory on Friday night, Tampa Bay pitchers limited Baltimore to two runs and 10 hits over 29 innings.
"The pitching has been outstanding," Maddon said. "We've gotten enough hitting. The defense has been great."
Promoted from Triple-A Durham earlier in the day, Romero gave up Manny Machado's leadoff single starting the game. But that was the only hit off Romero, who walked four and struck out none in 4 2-3 innings.
"Very happy to stay here with the Rays," Romero said. "I appreciate the Rays called me."
Romero was home Saturday when he got a call from his agent saying the Rays wanted him pitch the next day. He played catch before heading to the airport to catch a flight to Florida.
Brandon Gomes (3-1) replaced Romero with two on and two outs in the fifth and struck out Machado.
"Enny pitched unbelievable, so it would be a waste to have that not come through with a win," Gomes said.
Romero went 11-7 with Double-A Montgomery before throwing eight scoreless innings for Durham on Sept. 2. He also pitched out of the bullpen for the Bulls on Sept. 13 in the International League playoffs.
Tampa Bay's original scheduled Sunday starter, Jeremy Hellickson, came out of the bullpen Friday night and threw 2 1/3 scoreless innings for the win.
Scott Feldman (5-5) gave up three runs and six hits in 6 1/3 innings.
"Basically we're going to have win out and hope for the best on the other side," Orioles centerfielder Adam Jones. "We battle and we grind, and sometimes, as the saying goes, you're the bug and sometimes you're the windshield. The last couple days we've been the bug so we just have to get back to being that windshield."
David DeJesus put the Rays up 1-0 on a leadoff homer in the first, a 10-pitch at-bat. It was his first homer since connecting on June 13 for the Chicago Cubs.
Rays third baseman Evan Longoria, hitting .263 with 29 homers and 77 RBIs, was a late scratch due to flulike symptoms. He entered in the eighth inning as a defensive replacement.
Tampa Bay centerfielder Desmond Jennings, who reached on a bunt single in the sixth, left with left hamstring tightness after running toward second on a foul ball. He was scheduled to undergo an MRI
Maddon would like to see the wild-card playoff expand from one game to best-of-three. For those worried about making the season longer, Maddon thinks playing a doubleheader during the series could be a viable option. ... Orioles RHP Chris Tillman, who hurt an ankle during Thursday's game against Boston, remains scheduled to make his next start Tuesday. ... The Rays are expected to activate RHP Jesse Crain (right shoulder strain) on Monday. ... Tampa Bay selected the contract of RHP J.D. Martin from Durham to provide additional bullpen depth. He is expected to be designated for assignment Monday.