Lynn has won his first three starts, giving up a total of three runs in those appearances. He struck out four and walked one before leaving with his team in front by a lone run.
Mitchell Boggs struck out two while working a perfect eighth and Jason Motte walked one in the ninth on his way to his third save.
The only run off Lynn came on a first-inning, inside-the-park homer by Alex Presley. St. Louis center fielder Skip Schumaker slammed into the wall trying to make a catch of Presley's long drive and collapsed while Presley circled the bases.
Schumaker eventually left the field and was replaced by Erik Komatsu.
A solo homer by Daniel Descalso and an RBI double by Rafael Furcal in the ninth gave the Cardinals some insurance.
Charlie Morton (0-1) suffered the loss while giving up two runs on four hits with six strikeouts in five innings. The run scored by Lynn in the fifth was unearned due to a throwing error that prolonged the inning.