The game will be made up on July 13 at 1 p.m. as part of a split doubleheader.
The rainout comes at a time when the first-place Rays were treading water following a 14-4 start. Tampa Bay has lost three of five and was 7-8 in its last 15 games.
The Rays won the opener of the three-game series on Friday night before managing only three hits Saturday night in a 3-0 loss to the last-place Orioles. It was the fifth time in nine games that Tampa Bay was held to two runs or fewer.
Still, the Rays are in a far better place than last year at this time. Their 21-12 record was second-best in the majors at the start of play Sunday and represented a vast improvement over the 15-18 record they carried after 33 games in 2018.
In addition, Tampa Bay had a major league-best plus-43 run differential, was 8-1-1 in series play and still hasn't lost a road series since Aug. 17-19, 2018, at Boston.
As the rain poured onto the field at Camden Yards on Sunday morning, both managers expressed hope that the game would be played.
''We'd rather play. We'd like to play. We're here,'' Tampa Bay's Kevin Cash said.
Baltimore rookie manager Brandon Hyde said, ''When you get the pants on and the uniform going and you start getting into your routine, you'd rather just play the game.''
Afterward, Cash said: ''Obviously, it was tough. A lot of rain in the forecast, a lot of rain earlier this morning. It didn't look like it was going away.''
The Rays recalled LHP Ryan Yarbrough from Triple-A Durham and optioned RHP Casey Sadler. Yarbrough went 16-6 as a rookie in 2018 but had a 9.95 ERA this year before being optioned on April 24.
Rays: INF Matt Duffy (left hamstring tightness) was slated to play five innings at 3B on Sunday in his second rehabilitation game with Class A Charlotte.
Orioles: RHP Alex Cobb (lumbar strain) is playing catch to keep his arm in shape but is still resting his back and hip.
Rays: Blake Snell (2-3, 4.31 ERA) will help Tampa Bay open a three-game interleague series against visiting Arizona on Monday night.
Orioles: Sunday's scheduled starter, John Means, will start Monday night in the opener of a three-game series against the Red Sox.
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