Niemann (1-0) walked two and struck out a pair in his second spring training outing.
The Rays scored three times against Phillies' starter Cole Hamels (0-1) in his third and final inning. The lefty struck out two, walked one and saw his ERA jump to 12.60.
Jason Bartlett led the Rays' offense with two hits in three trips to the plate scoring a run and knocking in one.
Tampa Bay blew the game open in the seventh and eighth off reliever Carlos Carrasco wit worked an inning and two-thirds allowing six runs and five hits. He hurt himself with four walks.
Fabio Castro was superb for Philadelphia working three scoreless, hitless frames.
NOTES: Due to rainouts and shortened games, both teams played on after the game was official to get in some additional work. The Phillies received a call from the Rays and brought extra players to St. Petersburg to accommodate the extra innings.