WASHINGTON – Summoned by the Twins for a fill-in start Sunday, Tyler Duffey gave up a run in the first inning, but he settled down after that and matched Stephen Strasburg inning-for-inning until the fifth.

That's when Matt den Dekker lined a pitch back up the middle that struck Duffey in his right shoulder.

Duffey tried to shake if off as Twins manager Paul Molitor and trainer Dave Pruemer checked on him. Duffey was removed as a precaution, meaning the Twins had to use all seven of their relievers the rest of the way in their 6-5, 16-inning loss to Washington.

Duffey was diagnosed with a contusion on the shoulder. "I'll play catch [Monday]," he said. "It doesn't hurt or anything. It's just swollen."

Duffey's recovery is an issue as the Twins decide whether Ervin Santana is ready to pitch after dealing with a sore back that forced him to sit out his scheduled start Sunday. Santana's back has improved, but he will have to throw in the bullpen before he's allowed to return to the rotation.

It's unlikely Santana will be ready to pitch during the upcoming series vs. Cleveland, but he could return in time for the weekend series vs. Detroit.

"The worst-case scenario is that he doesn't rebound and we are going to have to consider disabling him," Molitor said.

If that happens, the Twins would need a fill-in starter again.

Duffey was sent back to Class AAA Rochester after the game, but the Twins can call him right back up if Santana needs to go on the DL.

Santana said he plans to play catch Monday and see how his back responds.

Decision time nears

If and when the Twins decide to bring up veteran David Murphy, his role is expected to be as an extra outfielder and not a starter.

The Twins have until Sunday to call Murphy up from Rochester or grant him free agency. That was part of the deal when they signed him April 14. At the time of the signing, the young outfield of Eddie Rosario, Byron Buxton and Miguel Sano was underperforming across the board. Since the signing, Sano has surged and Rosario has showed signs of life at the plate.

The Twins still believe Murphy can bring something they don't have. "The main goal of his signing was the fact that we're looking for a little bit more experience in our outfield," Molitor said. "We really don't have that. They are all relatively young. [Oswaldo] Arcia's got the most experience and he barely was in the big leagues last year.

"It was just more of an experienced guy, to be able to have a good at-bat whether it is off the bench or a spot starter. A guy who knows how to play the game."

Murphy is 5-for-32 (.159) in nine games at Rochester.

Assistant GM Rob Antony said the Twins remain confident Murphy can help offensively if called upon. "He takes good at-bats," Antony said. "Looks like he's knocking the rust off."

If Murphy comes, someone has to go. Buxton is struggling the most among the starting outfielders — hitting .150 with 20 strikeouts in 40 at-bats — but the Twins have leaned toward letting their top prospect learn how to hit major league pitching. Arcia is batting .258 with two home runs and five RBI in a reserve role, but he has faltered defensively. He would have to clear waivers before being sent to the minors.

"Everything is so fluid," Antony said.

Meanwhile, the Twins will announce a roster move Monday as utilityman Danny Santana (right hamstring) will be activated from the DL. The move was going to be announced Sunday, but with so many pitchers worn out from the 16-inning loss — and some just being ineffective — the Twins will discuss more moves.