Freshfields Bruckhaus Deringer is advising Paddy Power Betfair on its proposed merger with US fantasy sports website FanDuel.

City corporate Oliver Lazenby is leading the Freshfields team advising the FTSE 100 gambling company, with the news of the proposed merger coming after a landmark ruling from the US Supreme Court which could legalise sports betting across the country.

Paddy Power Betfair is understood to be taking US advice from Philadelphia-based firm Blank Rome.

Freshfields has a longstanding relationship with Betfair and in 2015, Lazenby and senior partner Edward Braham led the firm's team on its merger with Paddy Power, which was advised by Irish firm Arthur Cox.

Blank Rome's US team was led by business litigation partner Dennis Ehling and corporate partner Peter Schnur.

The magic circle firm also advised Betfair on its £1.39bn initial public offering in 2010, the sale of a 23% stake to Japan's SoftBank Corporation in 2006 and private equity firm CVC Capital Partners' failed takeover in 2013.

FanDuel, meanwhile, is understood to have turned to US firm Wilson Sonsini Goodrich & Rosati and Scotland's Shepherd and Wedderburn for advice on the tie-up.

FanDuel's links to Scotland derive from its founding in Edinburgh in 2009 as part of Hubdub, a news prediction platform that allowed users to bet with virtual money on important events, but which closed in 2010 to allow the its founders to focus on FanDuel's US operations.

In a statement, Paddy Power Betfair said: "Discussions are ongoing and there is no certainty as to whether agreement will be reached, or as to the terms or timing of any transaction."

Paddy Power Betfair made its first foray into the fantasy sports market last year when it acquired US competitor Draft for $48m.

A proposed merger of FanDuel and fantasy sports rival DraftKings was discarded last year after being blocked by the Federal Trade Commission, which cited that the combined company would hold a 90% market share.