Hammonds shown half-time red card during Portsmouth FC talks

Sulaiman Al Fahim, chief executive of Hydra Properties and leader of the bidding group, initially instructed Hammonds but switched to Mayer Brown after an apparent disagreement over fees.

Mayer Brown corporate partner Rob Hamill is now advising the Al Fahim-led consortium as the takeover enters the vital due diligence stage.

Taylor Wessing partner Tim Stocks is acting for Devondale Investments, the investment vehicle of owner Alexandre Gaydamak, who became the majority stakeholder in the Premier League club in 2006. Gaydamak is receiving separate advice from Sherrards partner Jean-Paul da Costa.

Hammonds had previously worked opposite Al Fahim on the £200m takeover of Manchester City last year. The firm represented the club during the successful bid by the Abu Dhabi United Group (ADUG), a deal brokered by Al Fahim.

ADUG was represented by Shearman & Sterling City corporate partner Laurence Levy.

Insiders at Hammonds said the firm lost out on the Portsmouth bid because Mayer Brown undercut its fees.

The Portsmouth takeover itself has been mired in ­controversy. Al Fahim has so far not revealed the ­identity of the investors backing his bid, while players have expressed concern at the length of time taken to finalise the deal.

French investor Gaydamak instructed niche firm Stock Fraser Cukier when he took control of the club in 2006.

Hamill said Al Fahim was an existing client of Mayer Brown. The firm also acted for the Football Association (FA) in an employment ­tribunal claim brought by former FA PA Faria Alam.