Armstrong (neck) began a rehab assignment with Triple-A Durham on May 16 and has struck out six over six innings while allowing two runs on one hit and two walks through his first five appearances.
Since he's been sidelined since spring training with the neck injury, Armstrong will be eligible for activation from the 60-day injured list whenever the Rays deem him ready. The right-hander has looked sharp over the course of his rehab assignment and could work his way back into Tampa Bay's late-inning mix, which looks more unsettled at the moment after closer Pete Fairbanks (hip) was placed on the 15-day IL on Monday.