American Debbie McDonald moved into contention for an individual dressage medal with an energetic, fault-free round on Brentina that scored 74.840 percent.
The ride moved her from fifth after the team competition on Saturday to fourth overall, with an average for the two days of 74.067 percent.
"I'm staying in the hunt," said McDonald. "It's a long shot, but I'm not giving up."
The United States hasn't won a medal in individual dressage since 1932.
The Americans had three steady rides, outscoring Germany across the board. Their scores were better than the ones they posted on Saturday, when the Americans took bronze behind Germany and Spain in the team competition. Germany has won the team gold in every Olympics since 1976, except the boycott year of 1980.
The individual medals will be decided by a combined total from the Grand Prix team test, yesterday's Grand Prix Special, plus the musical freestyle tomorrow.
German Ulla Salzgeber on Rusty still led the competition, but they made several mistakes and scored 74.840 percent to tighten the standings.
American Robert Dover scored 74.04 percent on Kennedy to move up from ninth to sixth with an overall percentage of 72.833.
"That ride was fun," Dover said. "Every day I've learned how much trust I can have in him."