Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_2151643_3 (opponents VARCHAR, outcome VARCHAR, surface VARCHAR)

### Question ###
Who were the opponents that led to an outcome of winner on a grass surface?

### Accurate SQL ###

SELECT opponents FROM table_2151643_3 WHERE outcome = "Winner" AND surface = "Grass"