A potential tussle is brewing between a likely Broadway revival of “Waiting for Godot” and incoming tuner “9 to 5,” both of which hope to open on April 30, the eligibility cutoff date for the season’s Tony Awards.

“Godot,” a developing spring production from Roundabout Theater Company that would star Bill Irwin and Nathan Lane, would take the place of “Dancin’,” a revival of the 1978 Bob Fosse dance-ical previously announced for Studio 54. (Although word of “Godot” has leaked out, the Roundabout did not confirm.)

The Broadway League, the trade association of producers and presenters that oversees the Rialto opening sked, has no formal rules stating two shows cannot open on the same night. In general, producers reserve dates as early as they can and then sometimes juggle the schedule so as not to dilute press coverage with concurrent openings.

Because the Tony ceremony is skedded to take place a week earlier than it has in recent years, the eligibility deadline is also moved up. Last season the cutoff was May 7.

Currently trying out at the Ahmanson in Los Angeles, “9 to 5” had originally been set for an April 23 Gotham opening at the Marquis Theater, following the January closing of the limited run of “Irving Berlin’s White Christmas.” It’s said, however, that the Nederlander Org, which owns the Marquis, has decided to book a short engagement at the venue for a Chinese circus troupe, skedded for the interim between the two productions.

The addition causes “9 to 5,” which has a technically complicated set that has proved occasionally unreliable in L.A., to lose some of its previews. Perfs had been set to kick off March 24, but are now planned to begin April 7.

“Dancin’,” meanwhile, had originally been announced for a May 5 opening, then moved back when the Tony eligibility schedule was confirmed. In recent weeks the production had been rumored to be up in the air, with a revival of “Side Show” also said to be a potential replacement.

Irwin (“Rachel Getting Married”) had initially planned to star in “Godot” this winter in a production at Seattle Rep that would have gone on to Broadway, but that plan was recently scrapped when commercial producer Elizabeth I. McCann (“Passing Strange”) pulled out.

The switch from “Dancin’ ” to “Godot” could, at least, save the Roundabout some money in a tough economic climate. Whereas “Dancin’ ” is a musical with a large cast, Samuel Beckett’s existential landmark “Godot” requires only four thesps.

Reps for both “9 to 5” and the Roundabout had no comment.