Cole De Vries’ bullpen session was going great through the first 20 pitches or so, all fastballs. Then he tried a curveball.

Now he’s on the disabled list.

“It just came right back again,” De Vries said of the tightness in his right forearm, a discomfort that the Twins will examine with an MRI on Monday in Minneapolis. “It’s not a pain where you go, ‘Oh my gosh.’ ... I could throw with it, but it would be very uncomfortable. And I don’t want to make it worse.”

Neither do the Twins, so Pedro Hernandez, the lefthander acquired from the White Sox for Francisco Liriano last July, will be called up from Class AAA Rochester in time to make De Vries’ start against the Orioles on Sunday. Hernandez has pitched in only one major-league game, giving up eight runs in four innings to the Red Sox while pitching for Chicago last July 18. But he did not allow a run in 11 innings during spring training, and was scheduled to pitch for the Red Wings on Sunday anyway.

It may be only a one-game fill-in, too; De Vries can be placed on the 15-day disabled list retroactive to his last appearance on March 29, and lefthander Scott Diamond is scheduled to return to the Twins next week if his tune-up start for Class A Fort Myers goes well on Sunday.

As for De Vries, “It’s pretty disappointing,” he said of the first arm injury he’s ever suffered. “But my curveball and slider are two of my best pitches. I don’t want to be trying to get major league hitters with half of my pitches. Hopefully, it’s just a strain and I’ll be right back.”

Once is not enough

Liam Hendriks cruised through the Orioles’ lineup the first time he faced them, retiring eight of the nine hitters. But he tried to be too perfect, he said, the second and third time through, and it cost him.

Hendriks allowed four runs in the 9-5 loss and didn’t make it through the fifth inning in his 2013 debut. “I was just trying to throw a good slider, good curveball early in the count, then I’d try to throw a better one,” the Aussie righthander said. “I nibbled too much. Gripped it a little too hard on my offspeed stuff when I was ahead in the count.”

It was a 3-2 pitch that cost him the most, though, a fifth-inning fastball that Adam Jones drove over Aaron Hicks’ head in center field for an RBI double. “It was meant to be low and away. I was trying to throw a strike and left it up,” Hendriks said. “I’m surprised it stayed in the park. The way it left the bat, I thought it was gone.”

It wasn’t what Hendriks hoped for, but at least it was far better than his visit here last season. Hendriks came down with food poisoning during the Twins’ series here, and spent three nights in a hospital.