After making his Premier League debut against Manchester City in midweek, Tau started from the substitutes’ bench as Neal Maupay led the line for the Seagulls.
Maupay justified his inclusion as early as the 17th minute when he managed to get on the end of a square-ball from Alexis Mac Allister to tap into an empty net.
Brighton could’ve had a second after a few minutes through Leandro Trossard but after waving through the byline, saw his attempt deflect onto the crossbar.
The visitors found more chances for a comfortable advantage at the break, but a combination of poor finishing and decision-making saw the opportunities go astray.
Maupay leaned towards a brace a minute from the restart from a ball by Mac Allister though after carving an angle, dragged wide from a promising area.
Leeds started to venture forward midway in the second half when a corner-kick from Raphinha picked out Liam Cooper at the back-post, but Brighton goalkeeper Robert Sanchez parried.
Sanchez remained busy seconds later after he pushed to the near side of the area to spurn a fiery shot by Patrick Bamford following a swift counter-attack.
It was time for Tau to enter, as the former Mamelodi Sundowns star replaced Trossard following the 73rd minute with the tie firmly in the balance.
Brighton enjoyed a lot of openings following the closing minutes of the match, but Leeds goalkeeper Kiko Casilla refused to open up however the Seagulls still claimed victory.