SAN FRANCISCO, Sept 22 | Sun Sep 22, 2013 2:03pm EDT SAN FRANCISCO, Sept 22 (Reuters) - America's Cup racing is set to resume on Sunday with Emirates Team New Zealand just one race short of claiming the trophy from Oracle Team USA. After struggling for much of the regatta's final series in San Francisco, the team owned by Oracle Corp. co-founder Larry Ellison has gained momentum against Emirates Team New Zealand, refusing since Thursday to let the Kiwis win the one race that would give them the trophy. Uncooperative weather conditions on San Francisco Bay wreaked havoc on the race schedule last week and most recently forced the postponement of two races scheduled for Saturday. Organizers said they expect the wind to start light and build through the afternoon for Sunday's two planned races, reaching about 20 knots (23 mph), which would be under the wind limits that have halted racing several times during the regatta. But a new potential wrinkle surfaced Saturday n...