DETROIT — James Shields allowed two hits over seven innings in another terrific performance, and the Kansas City Royals edged Detroit 3-0 on Wednesday night to take a one-game lead over the Tigers atop the AL Central.Shields (14-7) gave up a single to Ian Kinsler leading off the first. Then he picked off Kinsler — and retired every other batter he faced until another Detroit single in the seventh. The Tigers put two on that inning, but Shields worked out of the jam.Kelvin Herrera pitched the eighth and Wade Davis finished for his third save.Rick Porcello (15-11) pitched well for the Tigers, but Kansas City pushed across two runs in the fourth on RBI singles by Salvador Perez and Lorenzo Cain.Alcides Escobar added a sacrifice fly in the ninth.Detroit won the first two games of the series to pull into a virtual tie for first in the division, but the Royals avoided a sweep.