Yunel Escobar and Eric Thames knocked in runs for Toronto, which had the tying run on third base in the eighth inning, but the Jays lost 4-3 to Minnesota on Sunday, settling for a split of their four-game series.
Romero allowed nine hits in 5 1-3 innings, walked five and did not strike out a batter for the first time in 101 career starts. He threw only 51 of his 99 pitches for strikes.
"It's mechanics," he said. "I'm rushing through my delivery. I worked on it all week. This game just tests you sometimes mentally. You just got to stay mentally strong and just continue to work."
After winning three of his first four starts with a 3.29 ERA, Romero is 1-1 in his last four with a 4.50 ERA, allowing 13 runs in 26 innings. Additionally, he has walked 15 batters.
"We've got to get Ricky right. He's not been sharp in two starts in a row. The walk totals have been abnormally high for him," manager John Farrell said. "It seems like his arm's not catching up. It's a matter of staying over the rubber a little bit longer and allowing his arm to catch up."
Romero allowed a home run to Brian Dozier in the third, but Minnesota added three more in the fifth.
Denard Span and Dozier singled before Joe Mauer walked to load the bases with no outs. Josh Willingham walked and Doumit followed with a two-run single up the middle. It was Minnesota's only hit with runners in scoring position over its past 19 opportunities.
"We faced a very good pitcher, Romero's going to make you work," Minnesota manager Ron Gardenhire said. "We made him work pretty hard and we got his pitch count up, so it says a lot about the way we had at-bats, we made him throw pitches, but we couldn't finish him off. We had an opportunity to open it up."
Still, that seemed like plenty the way Blue Jays batters were struggling to get hits against Scott Diamond of Guelph, Ont (2-0).
Diamond worked ahead in the count, moved the ball in and out and primarily kept the ball down in the zone. He allowed five hits and struck out four without a walk.
"I was getting hit hard, but our defence came up big for me," he said. "I'm not a strikeout guy, so I just want them to keep hitting the ball in play and we were able to get some outs."
Diamond was hit with a line drive on his pitching shoulder in the second inning, but he kept stretching in the dugout between innings.
Toronto's offence got going in the eighth.
After RBI singles by Escobar and Eric Thames off Jared Burton, another run scored on a wild pitch by Glen Perkins. But Brett Lawrie grounded out with the tying run on third.
"We got a bunch of fighters. We don't give up until the last out," Davis said. "Unfortunately we came up on the wrong side."
The Blue Jays finished a 10-game trip to Los Angeles, Oakland and Minnesota with a 5-5 record.
"We played pretty solid baseball all the way around," Farrell said. "You'd like to come back 6-4, but I'm not going to take away anything from anybody. We're playing competitive baseball. We're bringing it every day and we got to go home and get things going."
NOTES: Toronto turned two double plays for a league-best 45. ... Davis had two of Toronto's four stolen bases. ... Minnesota's Trevor Plouffe ended a 0-for-11 skid with a seventh-inning double. ... Minnesota opens a two-game homestand against Cleveland on Monday. Carl Pavano (2-3, 5.02 ERA) will take the hill for the Twins against Jeanmar Gomez (2-2, 4.66). Pavano said Sunday he recently had an MRI that revealed a strained shoulder, but that he's good for Monday. ... Brandon Morrow (4-1, 2.27) is scheduled to start Monday when the Blue Jays return home to face Tampa Bay, which will counter with Jeff Niemann (2-3, 3.48).