Jordan Lyles delivered a quality start but the Orioles at-bats too often lacked true quality and they were blanked 3-0 by the Washington Nationals.
The Orioles were shutout for the fifth time this year as earlier they were blanked by the Rays, Tigers, Yankees and Mariners.
Baltimore beat Tampa Bay on Friday with one run on five hits and again won Sunday with just two runs on four hits. But winning again with four hits was a bridge too far.
The O's were held to four hits - Ryan Mountcastle reached on an error in the ninth that was later changed to a single - and had one runner get into scoring position all night.
That was catcher Adley Rutschman, who reached on a two-bagger with 106 mph exit velocity in the seventh. But he was stranded as they lost the opener of the brief two-game interleague series.
The Orioles are clearly playing better overall and certainly better within the AL East, but they have had trouble getting on an extended roll this season. Entering Tuesday's game they had won three of four and six of nine. They were 8-6 in the past 14 and 16-14 in 30 games since May 19.
But the Nationals, who were 24-46 at game time, with just three wins in their past 14 games, got the victory on this night.
Right-hander Erick Fedde allowed two hits over six innings as the O's went 2-for-20 at-bat against him. He seemed an unlikely candidate to pitch such a gem with an ERA of 8.47 his previous four outings. And he had thrown six innings in just two of his first 13 starts to this season.
But he faced the Orioles for the third time in his career and has an ERA of 0.52 in those games, allowing one run over 17 1/3 innings.
Lyles allowed two runs and five hits over 6 1/3 innings, throwing well yet again in a home start. While his road ERA is 6.70, his home ERA is 2.92 after Tuesday's game and he has not allowed a single homer at Oriole Park in 37 innings.
He produced the Orioles' 15th quality start last night and third in the last five games. The O's are 10-5 when they get a quality start. But they are winless when they get no runs.
On the farm: Infielder Jordan Westburg hit another homer for Triple-A Norfolk and it was a three-run shot as the Tides lost 10-7 at Lehigh Valley. That was Westburg's only hit in five at-bats and he's now batting .383 with an OPS of 1.229. In his first Norfolk game, infielder Jonathan Araúz went 3-for-5 with a two-run double.
Lefty DL Hall struggled with his control and gave up four hits and five runs (two earned) with five walks and three strikeouts over 4 1/3 innings. He ran his pitch count to a season-high 92, but again failed to get to or past five innings, something he has done once with the Tides. His ERA is 3.86 in nine starts.
Erie routed Double-A Bowie 11-0. Right-hander Garrett Stallings, who had an ERA of 2.63 in early May, is now 2-6 with an ERA of 8.87. Last night he allowed seven runs in 1 1/3 innings and he has allowed 33 earned runs in 13 2/3 over his past five starts.
On his injury rehab assignment, outfielder Yusniel Diaz went 2-for-2 for high Single-A Aberdeen with a homer and sac fly. But the IronBirds (43-21) lost 7-3 at Wilmington.
Low Single-A Delmarva routed Lynchburg 12-6, getting three RBIs each from Isaac De Leon and Noelberth Romero, who hit a two-run homer. Heston Kjerstad went 1-for-4 and is batting .400 with a .957 OPS.