PHOENIX -- Zach Eflin's great night on the mound had a sour ending Monday after the Baltimore Orioles right-hander left a game against the Arizona Diamondbacks because of shoulder fatigue.

Eflin gave up only one run and four hits over six innings, but his velocity dipped in the sixth. The 30-year-old mentioned the fatigue to manager Brandon Hyde between innings, which was enough to shut him down for the evening.

The Orioles beat the Diamondbacks 5-1. Eflin threw 73 pitches.

"We're going to get some tests done, and hopefully, keeping our fingers crossed, everything's OK there," Hyde said. "Because he was absolutely cruising and so efficient. We're hoping for the best tomorrow."

Eflin said he was "pretty optimistic" the issue wouldn't be a long-term setback, adding that his exit, he thought, was "precautionary. We'll evaluate it tomorrow, and see how I feel after sleeping tonight."

The Orioles have already lost key reliever Albert Suárez for a couple of months after the right-hander was moved to the 60-day injured list Monday because of a shoulder injury.

Eflin was 5-2 with a 2.60 ERA over nine starts for the Orioles last season after being acquired at the trade deadline in a deal with the Tampa Bay Rays. He is 2-1 with a 3.00 ERA through three starts this season.

"Listen, we won, 5-1, we played great defense, had an offensive game. It was a good day at the yard," Eflin said. "Unfortunately, I had a little bit of fatigue. But we'll see how it feels tomorrow."

The Associated Press contributed to this report.