Tau scored for Albion in the previous friendly at Luton Town last Saturday but was not among the 23 players involved for the final tune-up against Getafe.
The South Africa striker, who has made just one Premier League appearance for Brighton, looks set to join Egyptian top flight club Al-Ahly, where he would reunite with his former Mamelodi Sundowns coach Pitso Mosimane.
Tau, 27, has had little chance to impress at Brighton. He signed from Sundowns for around £3m in 2018 and had loan spells in Belgium with Union SG, Club Brugge and Anderlecht.
His loan at Anderlecht was cut short last season and the skilful left-footed attacker joined Graham Potter's team and made his debut in an FA Cup penalty shoot-out victory at Newport.
He made a decent Premier League debut at champions Man City and was then used as a second half substitute in the next match at Leeds.
Tau then didn't feature in the league until May, when he came on as a late substitute and claimed an assist with a nice throughball to Danny Welbeck during the 1-1 draw.
This season was always set to be now or never at Albion for the former Sundowns man and his excellent pre-season goal at Luton gave reason for optimism.
Tau was expected to see further first team opportunities at the start of this campaign, especially following the summer exit of Alireza Jahanbakhsh and the fact that Welbeck remains injured.
But the news that Al Ahly, who are second in the Egyptian Premier League behind Zamalek, and his omission from Albion's final pre-season match, suggests his Albion career is over before it ever started.
Former Leeds defender and South Africa skipper Lucas Radebe however thinks he should should stay with Brighton and fight for his place.
“I don’t think Percy must leave. I see no point in returning to Belgium because he’s been there before. He’s talented enough to play at Brighton. He must fight harder... show them he can do it,” Radebe said speaking to the Sowetan.
Brighton kick-off their Premier League on August 14 at Burnley.