Sophomore goalkeeper Raul Belman Romero collected three saves in the Blue Jays' narrow 1-0 loss to the Bears on Monday night.
Westminster College was outshot 16-6 in dropping to 2-4 on the season.
Washington's Jake Shapiro converted an unassisted goal in the 79th minute for the match's only score.
Blue Jays sophomore midfielder Drew Cook was named St. Louis Intercollegiate Athletic Conference offensive player of the week. Cook scored a pair of goals last week, including the game-winner in the Blue Jays' 1-0, double-overtime victory over Millikin (Illinois) University at home on Saturday.
Westminster plays at Augustana (Illinois) College at 1 p.m. Sunday.