The American billionaire has arrived in England as he seeks to finalise the Tornante investment group's Â£5.67m deal.
Meanwhile, Tornante's president and chief operating officer, Andy Redman, attended the Blues' friendly victory at Crawley on Saturday.
He accompanied Pompey chief executive Mark Catlin in the Broadfield Stadium directors' box and saw Kenny Jackett's side win 2-1 through two Brett Pitman goals.
In addition, Eric Eisner has tweeted of his arrival in England as the key players in the ownership bid gather.
The takeover timeframe has long pitched around the end of July and start of August for completion.
The Eisners have previously intimated they would be attending this weekend's League One curtain-raiser against Rochdale at Fratton Park.