Teheran (3-1) gave up five hits, one run — Josh Willingham's homer in the ninth — and one walk. He struck out four, throwing 80 of his 123 pitches for strikes.
Cory Gearrin earned his first career save by retiring pinch-hitter Oswaldo Arcia on a flyout.
Minnesota has lost six straight.
The previous longest career outing for Teheran was seven innings, a mark he reached in a no-decision April 29 against Washington and a May 9 victory at San Francisco.
After rallying in late innings to win three straight from the Los Angeles Dodgers over the weekend, Atlanta jumped on Twins starter Kevin Correia (4-4) early.
