The Twins lost 5-4 in the first game of a 3-game series against Detroit Monday night at the Metrodome.  Detroit scored 2 runs in the 7th inning and added 2 more runs in the 8th inning.  Matt Guerrier allowed 3 hits and 2 earned runs in 1 1/3 innings to take the loss and drop to 4-3.  Joe Mauer went 2-4 with a run scored and 2 RBIs, Denard Span went 2-4 with an RBI and Carlos Gomez and Alexi Casilla went 2-5 with a run scored.  Glen Perkins threw 6 1/3 innings with 7 hits and 2 earned runs allowed but didn't figure in the final decision.  The Twins are 45-38 and are now 2 1/2 games back of the White Sox for first place in the American League Central.  The Twins host Detroit again tonight at 7:10, pregame on WJON at 6:40.  Righthander Scott Baker (4-2) gets the start on the mound for the Twins and lefthander Nate Robertson (6-6) toes the rubber for the Tigers.