Fielder's two-run single capped a four-run Tigers outburst in the second inning, putting Detroit ahead to stay.
The first baseman later added a sacrifice fly and a solo homer while Omar Infante contributed a bases-empty shot on his way to three RBI as Detroit pounded out 15 hits in the one-sided victory.
Sanchez (6-5) rebounded from a rough start in his prior outing to stifle the Rays on one run, yielding just one walk while striking out nine. He tossed 65-of-102 pitches for strikes as the National League Central-leading Tigers took the opener of a three-game set.
Tampa Bay's Matt Moore (8-1), meanwhile, was handed his first loss in 12 starts to begin the season. The left-hander was lit up for six runs on seven hits in a two-inning appearance.
Desmond Jennings got the Rays' only RBI.