Maybe it was just Orioles magic.
Max Scherzer had retired 16 straight Orioles through the last of the eighth, but he exited after a season-high 119 pitches.
Nick Markakis started the ninth with a solo homer off Valverde and it was a 5-4 game. Singles by Adam Jones and Chris Davis put runners on the corners with none out. But two popouts followed and the Orioles were down to their last out.
That's when Dickerson got the crowd into a frenzy with a blast out to right-center field. It is his fourth homer of the year and produced one of the season's most dramatic victories.
The game attracted a crowd of 46,249, which is the third sellout of the season.
Miguel Cabrera went 2-for-4 with a two-run homer in the first for the Tigers. He now has a major league-leading 12 homers and 33 RBIs in the month of May.
The Tigers took a 5-3 lead on Miguel Gonzalez, who gave up five runs over six innings. But that lead would not last.
The Orioles, who have won eight of their last 11 games, improved to 14-12 at home and 31-24 overall.
In the second game of the weekend series, Saturday at 4:05 p.m., Jason Hammel (7-2, 4.98 ERA) faces Justin Verlander (6-4, 3.68 ERA).