The phrase "acts as manager" is correct and usable in written English.
You can use it to describe someone who is performing the duties or responsibilities of a manager, even if they do not hold the official title.
Example: "During the project, Sarah acts as manager, coordinating the team's efforts and ensuring deadlines are met."
Alternatives: "serves as manager" or "functions as manager."
Mr. Yeong Wai Heng, a relative of the proprietor, acts as manager.
The following Olympics brought even greater triumph as Cuba qualified for the quarter-finals in 1980, one of Moreno's last acts as manager before stepping back from the dugout and into the Cuban Football Association's offices in 1981.
There is a city manager for each county borough council, and for each county council there is a county manager, who also acts as manager for the lesser local authorities within the county.
A retired practitioner of the topless arts, Lily now acts as manager and den mother to the younger girls: a hard-drinking, hot mess played by Lisa Arturo, whose breasts-forward filmography includes no less than three characters named Candy; and a giggling ingénue played by Bre Blair, best remembered as one of the heroines in the 1995 film "The Baby-Sitter's Club".
Even when the Smiths became successful, Marr acted as manager, booking vans and sorting all the finer detail.
From his apartment, where Mrs. Dykshoorn acted as manager and gatekeeper, he had counseled them on business deals and love interests, on career decisions and used-car values.
The agencies act as manager, agent, and promoter, controlling every aspect of an idol's career: record sales, concerts, publishing, endorsements, and TV appearances.
The US Chess Federation had watched events in Sousse and Lugano with dismay, so its chief executive Ed Edmondson arranged to act as manager during the next championship cycle.
Its spirit pervades every aspect of Liverpool football club, to the point where Rafa Benítez's last act as manager was to donate £96,000 to the campaign.
