Paul Weiss Rifkind Wharton & Garrison has won a leading role on the high-profile dispute between chemicals companies Hexion and Huntsman.
The New York firm's chairman elect Brad Karp is advising Hexion alongside Wachtell Lipton Rosen & Katz on the damages litigation between the two companies.
The latest instalment in the long-running saga follows a court battle in Delaware that came to a successful end in late September for Vinson & Elkin client Huntsman. Hexion and its parent Apollo Management had filed suit against Huntsman in June, arguing that the combined company would be insolvent if the deal went ahead. Huntsman countersued.
Finding in favour of Huntsman at the earlier case the judge, Vice Chancellor Stephen Lamb, slamed Wachtell giving advice that led to the aborted $10bn (£6.46bn) merger of Hexion and Huntsman.
Hexion is facing damages of at least $325m (£209.85m) - the size of the break-up fee - and potentially billions of dollars after it lost its case in Delaware, with Lamb stating that the company had "knowingly and intentionally" breached several of its covenants under the merger contract.
The next stage of the battle is expected to commence today, when the merger transaction itself is scheduled to close. At this stage it looks like the lending banks are now unwilling to provide the money for the transaction.
"The chances of that happening are slim to none," said a lawyer close to the case. "That will trigger another round of litigation."
It is this subsequent round for which Paul Weiss is thought to have been brought in.
Another lawyer close to the case said: "The Delaware case was pretty hard on Wachtell and made specific references to the firm, which is not normal. The suggestion is that Paul Weiss would provide a 'fresh face'."
Wachtell's client is private equity giant Apollo, the owner of Hexion. Lamb took the unusual step of specifically criticising the New York firm, saying that an insolvency opinion Apollo had obtained was "unreliable" because it had been produced with the knowledge that "it would potentially be used in litigation, was based on skewed numbers provided by Apollo, and was produced without any consultation with Huntsman management".
Lamb added that Hexion had "knowingly and intentionally" breached covenants and effectively ruled the deal must go ahead.
Vinson & Elkins partner David Harvin is advising Huntsman while Marc Wolinsky is leading the team for Wachtell.
Cravath is representing Deutsche Bank and Credit Suisse in relation to the litigation, with partner Rich Clary lead counsel.