Larsson had a 3-1 lead in the first set before Williams fought back to tie it 3-3. The 24-year-old brought it to 4-3 before collapsing against William’s strong serve and losing 4-6.
Williams went on to an easy win in the second set, breaking Larsson’s serve twice and dominating her all around.
“It was really good to come here and win after a disappointing Wimbledon so hopefully this confidence will help me for the rest of the year,” said Williams, who was bounced early at Wimbledon by Sabine Lisicki.
Larsson said, “At the crucial points I wasn’t really present, which was a shame.”