The 21-year-old flier will join Socceroos Kusini Yengi and on-loan winger Sammy Silvera at the Championship outfit after agreeing terms on a multi-year deal.

Central Coast Mariners will receive an undisclosed fee for the Olyroos star, who will use the move as a likely springboard into the senior national team.

The prospect of Farrell and the attack-minded Jordi Bos operating in tandem down the left for the Socceroos in the near future already has fans salivating, assuming he makes an instant impact for Pompey under the tutelage of head coach John Mousinho. 

Australia boss Graham Arnold will be watching closely from afar as the A-League’s most impressive left-sided defender of recent seasons makes the transition to a far more exalted level, turning down a number of other offers elsewhere in Europe to join the Aussie throng at a club whose progressive free-flowing approach appears tailor-made for him.

Already spotted at Pompey’s training base, Farrell need only complete the formalities of a medical and some residual paperwork to seal the move. 

His impending arrival will place immediate pressure on incumbent left back Connor Olgivie, 28, who has been at Fratton Park for the past three seasons, with the Aussie’s pace, discipline, distribution and sharp tackling key reasons for Mousinho bringing him on board.