pinch-hit
verb [ I ] US uk/ˈpɪntʃ.hɪt/ us/ˈpɪntʃ.hɪt/
替补
to do something for someone because they are suddenly unable to do it
He was pinch-hitting for one of the regular TV sportscasters, and was a great success. 他替补一位定期露面的电视体育节目解说员，表现得极为出色。