The continuous co-existence in Colloquial Singapore English (Singlish) of the past tense alongside already, an aspect marker expressing iamitive functions (Olsson 2013), has not, to present knowledge, received an adequate explanation in terms of diachronic change. The two forms are often seen to overlap in function, but a more intensive survey reveals that only the completive functions overlap, the non-completive functions accounting for the majority of uses in present-day Singapore English. The bias in functions is considered to be the result of a renovation in contact grammaticalization, or a convergence towards the lexifier, often expressed in terms of decreolization in creole languages. The present study considers quantitative data of both completive and non-completive already across four diachronic time periods, concluding that the constant diglossic presence of the standard lexifier since colonization contributed to the convergence shown.