Internet giant Google has announced the resignation of one of its directors, Arthur Levinson, who is also on the board of computer maker Apple.
It comes two months after Google chief executive Eric Schmidt quit the Apple board because Google's interests were increasingly competing with Apple's.
The move was welcomed by the US Federal Trade Commission (FTC) which has been probing overlapping board memberships.
The two firms used to be seen as allies against the dominance of Microsoft.
However, they have started competing directly in recent years in areas such as mobile phones.
Under US law, no-one is allowed to serve on the boards of two companies which are direct rivals.
In May, the FTC began an investigation into whether the presence of Mr Schmidt and Mr Levinson on the Google and Apple boards could lessen competition between the two firms.
Mr Levinson, who is also chairman of biotech comapny Genentech, had been a Google board member since April 2004.
FTC chairman John Leibowitz said in a statement that both firms and Mr Levinson "should be commended for recognising that overlapping board members between competing companies raise serious anti-trust issues".
The former US vice-president, Al Gore, is the last remaining link between the two companies. He serves on the board of Apple and is an adviser to Google.